LibrePilot Forum

General Category => General Discussion => Topic started by: TheOtherCliff on November 22, 2015, 02:56:43 am

Title: Warning: At least some sellers are selling Revos with bad baros
Post by: TheOtherCliff on November 22, 2015, 02:56:43 am
Executive summary: Don't buy a Revo clone without reading this and knowing how to test it as soon as you get it.  I would bet that the same problems exist with the Sparky2 clones.

A friend with a Revo vertical stability issue had it turn out to be a bad baro chip.  The board came from an eBay seller, website affiliation unknown at this time.

I also talked with a forum user that had bought two Revos from banggood.  Both had bad MPU6000's (gyro/accel) and low res baros.  Note that the high resolution baro is spec'ed and required for proper Revo operation.

I have access to a Revo just received from thanksbuyer and have done some testing on it as well.  It also has the low resolution baro chip.  This particular board has good gyros, accels, and mags as far as a quick bench test can prove.

So bad clones are known to come from both banggood and thanksbuyer.  These two companies probably get their boards from the same place.  If you have bought a clone (Revo or Sparky2) please test and report back here (what you bought, when you bought it, what you know is broken, what you know works (e.g. it flies in Basic (Complementary) Attitude Estimation Algorithm)) until we have a good feeling for whether any boards from these sellers are OK.  Note that if this thread gets really long, I may delete replies and provide a summary.

I also have heard of clone boards overheating and failing for no apparent reason.

I suggest that you pay with a service that will help you get your money back.  I use PayPal, but had to twist some PayPal arms once, even though I was in the right.

Here is a graph that shows first the bad board plugged in and then a good OP non-clone board.  The difference in the average value isn't important.  The noise is what is important.  You can see that the first half is a much thicker mess than the second half.  In particular, if your graph is about 00,070 thick (top to bottom, about 97,830−97,760 for this graph) or thicker, you have the noisy low res baro.  If your graph is about 00,015 thick or less you have the good baro.

This is in Pressure kPa which is the default baro scope
(https://forum.librepilot.org/index.php?action=dlattach;topic=311.0;attach=589)

Note that the good part has a little curve to it.  That is because that board was just plugged in and is warming up.  Ignore the curve and pretend it is straight.

This is in Pressure Altitude which you can enable with Tools->Options->Scopes->Barometer if you know your way around in there.
(https://forum.librepilot.org/index.php?action=dlattach;topic=311.0;attach=587)
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: ggrif on November 22, 2015, 05:36:56 am
Thanks Cliff, will check out mine from BangGood later tonight and post results.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: Mateusz on November 22, 2015, 08:26:08 am
I bought from ebay fisher-hobby, revo with a case, it had good arm z mcu, was flyable in complementary mode, so I guess mpu/mcu were fine, but baro was broken. I had huge vertical oscillations in the altitude hold/vario mode, and on scopes baro had 4-6 meters error, while original revo with the same firmware (both temp calibrated and not) had error of 0.5-1m. Also my baro was not changing average readout while I moved FC up and down, original revo worked. I got refund from the seller after him trying to deceive me to close request before he pays back, suggesting that he can send another baro, or to try another software as deadline for opening request was approaching.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: ggrif on November 22, 2015, 08:33:38 am
Quick test tonight. The spread is about 12, so good baro?

edit: hmmm, actually more like 6, at least to my non electrical engineers eye! 

Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: Mateusz on November 22, 2015, 08:56:28 am
Quick test tonight. The spread is about 12, so good baro?

edit: hmmm, actually more like 6, at least to my non electrical engineers eye!

I only looked at BaroSensor.Altitude [m] on the left part of scope you can see Bad baro on the right part same scale you can see good baro after switching boards.

Bad baro (lowest 173.5, highest 182.5, difference 9 meters!)
Good baro (lowest 175.5, highest 177, difference 1.5 meter)
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: f5soh on November 22, 2015, 09:41:15 am
Baro spike can come from a bad powering, an overloaded/bad regulator or bad filtering.
Check if there is ripple on 3.3v regulated. (Revo has 3 regulators)
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: Mateusz on November 22, 2015, 09:57:26 am
Baro spike can come from a bad powering, an overloaded/bad regulator or bad filtering.
Check if there is ripple on 3.3v regulated. (Revo has 3 regulators)

Mine was not reacting to altitude change, it should I guess despite the noise, and I can't check now, I returned item and got refund.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: ggrif on November 22, 2015, 06:39:00 pm
Here are a couple of screenshots.  Maybe someone could do a little interpreting for me?
Something funky with BG Accel?
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: cato on November 22, 2015, 10:58:59 pm
I don't see a relevant difference in the two baro scopes, they both are in the same area. Some drift is normal, especially right after you started it. I did not ceck that on my revo, but I know the same behavior from my baro altimeters for biking and hiking.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: Mateusz on November 22, 2015, 11:20:25 pm
Yes, both plots show the same (yellow) response kPa. I don't know what it should normally show, before I returned my revo clone I only looked at BaroSensor.Altitude in [m] units. That should not jump more than ~1.5m from lowest to highest peak (see attached plot). Mine was jumping 9 meters and not reacting to change of altitude.

The correct baro under magnifying glass should have three lines of symbols, the first line should be MEAS and second MS561101BA03. That is high precision baro http://www.meas-spec.com/downloads/MS5611-01BA03.pdf (http://www.meas-spec.com/downloads/MS5611-01BA03.pdf).

If you see higher than expected noise, or your baro does not react to change of altitude (be careful not to rip off USB connector when testing), but your baro symbols are as above, then it might be cheaper capacitors (leading to ripple on power lines), cheap regulator or damaged baro.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: ggrif on November 23, 2015, 12:12:52 am
OK, thanks.
I finally figured out how to add the altitude widget after I posted.

Works fine I think, variation is only 0.6 m and reacts to 1 foot changes in altitude.

Looks like I may have a good one, we'll see how well and how long it flies in a week or two.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: xpantz on November 23, 2015, 12:31:52 am
Somebody is pre-selling their Revo clone.  (my OP account was PM'd with this info)

http://www.trianglequads.org/

Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: TheOtherCliff on November 23, 2015, 12:37:14 am
@ggrif It looks like your banggood Revo clone has a good baro (or maybe has good voltage regulators, we don't know the cause for sure yet as @f5soh points out).

It would be nice to find out that (if) it is caused by voltage regulators.  It is possible for a human to replace those.  :)  I jest, but I wouldn't try replacing a baro unless I had a lot of boards that were otherwise junk to me, and I have 4 sizes of kapton tape and a hot air station.

@xpantz And OP/NG is not happy...
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: ggrif on November 23, 2015, 04:25:54 am
@ggrif It looks like your banggood Revo clone has a good baro (or maybe has good voltage regulators, we don't know the cause for sure yet as @f5soh points out).

It would be nice to find out that (if) it is caused by voltage regulators.  It is possible for a human to replace those.  :)  I jest, but I wouldn't try replacing a baro unless I had a lot of boards that were otherwise junk to me, and I have 4 sizes of kapton tape and a hot air station.

@xpantz And OP/NG is not happy...

I would stay way far away from
Trianglequads.

As for OPNG, they quit making Revos over a year ago. So if someone wants to step in and fill the gap making an "expensive, outdated" controller for $46, more power to 'em.

Sorry, a bit off topic.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: mazevx on November 23, 2015, 11:06:51 am
We had a User in german Forum who had the same problems with his revo clone altitude oscilation about 10m while standing on the table inside the house, He fixed the problem by soldering a Filter capacitor direktly to Vccin at the baro did you try something like that?
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: ggrif on November 24, 2015, 12:47:39 am
A pic of the BangGood Revo, just for reference. I haven't flown it yet but several guys at RCG have them and are flying without issues, using RaceFlight FW.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: Bob13011 on November 24, 2015, 07:09:37 am
Hi
Received yesterday Revo and a GPS Ublox M8N from Banggood.
Set up on an old FPV quad with LibrePilot.
Tests ok. Everything works fine. End flight test done at night with attitude, rattitude, altitude hold and GPS Assist
I had a good night. Thanks!
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: Zrisst on November 24, 2015, 08:51:12 am
Hi
Received yesterday Revo and a GPS Ublox M8N from Banggood.
Set up on an old FPV quad with LibrePilot.
Tests ok. Everything works fine. End flight test done at night with attitude, rattitude, altitude hold and GPS Assist
I had a good night. Thanks!

That's the first kit I got. Except for the mag issue posted in other treads it works fine.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: hburke on November 24, 2015, 08:21:29 pm
Thanks for the info Cliff. I dont know how to test the baro like you did, but I bet a million dollars this is why my Revo clones didnt work. I didn't get mine from either of those sources though. I think I found mine on Amazon or ebay. How do i go about testing the baro like that? what software is it?

And the trianglequads thing is not fake guys. I have 2 of them. I cant find the picture i took, but i posted it somewhere on RCG. I got them a while back from the makers and they are just like the OP Nano. i have one of the real ones that came from the OP store. I keep seeing people saying they arent real or it's a scam, but the guys that made them are in the USA and good guys. I would have said something about them earlier but they asked me not to say anything to anyone because they were not going to sell them. Scott gave me mine, I just had to pay shipping and actually i only asked for one and he sent me 2. i guess i told him my brother also was into drone racing so he sent 2 of them. i honestly cant tell any difference between my nano and their board and i used our GCS to set it up. Which works great btw :-)

I would highly recommend it over a Revo clone, both revo clones i bought were a bust. I stayed in lines for hours so to speak for the OP Nano and i loved it when i got it, but now i cant get anymore and triangle quads fell out of the sky in my lap like an angel :-D  .. the board is obviously high quality. it looks nothing like the cheap cc3d or revo clones i have had. i bought 2 more and i'm ordering another 2 today or tomorrow because my brother will not stop asking me for one and our friend that flies with us wants one. i for one am glad we have a source now.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: TheOtherCliff on November 24, 2015, 09:39:19 pm
We had a User in german Forum who had the same problems with his revo clone altitude oscilation about 10m while standing on the table inside the house, He fixed the problem by soldering a Filter capacitor direktly to Vccin at the baro did you try something like that?

One of the devs has gone so far as to replace the baro, the baro power filter capacitor (several values), and the regulator on a Sparky2 clone, and the scope still shows a large amount of noise.  There are still some things he is checking in to.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: TheOtherCliff on November 24, 2015, 09:42:40 pm
A pic of the BangGood Revo, just for reference. I haven't flown it yet but several guys at RCG have them and are flying without issues, using RaceFlight FW.

Using RaceFlight FW sounds like they are not using the baro.  For LP firmware, the baro is only used in altitude hold/vario throttle modes or in GPS flight modes.  Do racers use baro at all?
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: ggrif on November 24, 2015, 10:46:51 pm
Good point. Probably not.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: Brian on November 25, 2015, 02:07:39 am
I solved the issue, at least for the Sparky 2 clones.  The Sparky 2 schematic that I have specs an LP2992 voltage regulator, but my board has a MIC5219.  The different regulator isn't a problem, in fact is supports higher current, but it is not necessarily a drop-in replacement for the LP2992.  For example, the MIC5219 suggests a 470pF capacitor for a bypass capacitor, and the LP2992 specifies 10nF, which is what is on the Sparky 2 schematics.

My guess is that the cloners replaced the voltage regulator without changing the capacitor values and installed a 10nF capacitor, which is 20 times higher than recommended.  I believe this is causing the voltage regulator to not regulate properly and was causing the (relatively) low frequency noise on the Vcc line, and was causing the fluctuations in the baro readings.

I completely removed the capacitor and now the baro is stable to within about a meter, which is much better.  The MIC5219 will work without a bypass capacitor, but a 470pF capacitor could help lower the noise even more.

The bypass capacitor is the small capacitor directly in front of the regulator.

I somehow fried my Revo clone, so I can't test if that has the same problem, but it is probably worth investigating.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: TheOtherCliff on November 25, 2015, 02:29:15 am
That's great news!  Brian put a lot of work into debugging this for us.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: JaeMelo on November 29, 2015, 03:43:14 am
I solved the issue, at least for the Sparky 2 clones.  The Sparky 2 schematic that I have specs an LP2992 voltage regulator, but my board has a MIC5219.  The different regulator isn't a problem, in fact is supports higher current, but it is not necessarily a drop-in replacement for the LP2992.  For example, the MIC5219 suggests a 470pF capacitor for a bypass capacitor, and the LP2992 specifies 10nF, which is what is on the Sparky 2 schematics.

My guess is that the cloners replaced the voltage regulator without changing the capacitor values and installed a 10nF capacitor, which is 20 times higher than recommended.  I believe this is causing the voltage regulator to not regulate properly and was causing the (relatively) low frequency noise on the Vcc line, and was causing the fluctuations in the baro readings.

I completely removed the capacitor and now the baro is stable to within about a meter, which is much better.  The MIC5219 will work without a bypass capacitor, but a 470pF capacitor could help lower the noise even more.

The bypass capacitor is the small capacitor directly in front of the regulator.

I somehow fried my Revo clone, so I can't test if that has the same problem, but it is probably worth investigating.

This maybe the case for the Sparky2 FC but I can tell you for sure this is not the case for the Revo. I own the original Revo that comes in those cute little OP boxes, a scratch built revo using an OSHPark PCB with components from Digikey/Sparkfun in addition to the two types of cloned revos available on the market. There are two different kinds of cloned revos which are floating around. One which follows the original OP gerber/schematics and components and another which doesn't at all. The one that doesn't follow the original OP gerber works perfectly fine like my real revo but looks extremely cheap and has german colored header pins. The other clone that actually follows the original OP gerber/schematics and components has given me mixed results between the 5x boads of this particular kind that I've owned in total. Some of them are good with stable baro readings while some of them are total garbage. The point is both of the different types of clones use the exact same 400mA LDO regulators and have 10uF caps on the baros VCC side. So that rules out a difference in regulators/caps for the revo clones. The only thing I can think of are the caps are either junk on some units or the baro is the culprit. I won't know for sure until I dig deeper. I will swap components around tonight between the crappy clone and the good working one and will respond with my findings. I'll also post pics of these revos SBS so you can see the differences.

In the picture below from left to right is the:
Hand Built Revo(OSHPark) => Clone1(FollowsOPGerber) => Clone2(ModifiedOPGerber)
(http://imagizer.imageshack.us/v2/1024x768q90/903/P0yHjM.jpg) (https://imageshack.com/i/p3P0yHjMj)

In the picture below shows the two clones SBS... Noticed the difference in components and their placement.
(http://imagizer.imageshack.us/v2/1024x768q90/911/1HyOdO.jpg) (https://imageshack.com/i/pb1HyOdOj)

And this pic just shows my two builds. The hex has the real OP Revolution under the hood that is missing in the first pic while the quad has one of the Clone1 Revos shown in the first picture, but with perfectly stable bro readings.
(http://imagizer.imageshack.us/v2/1024x768q90/908/rE3BPu.jpg) (https://imageshack.com/i/p8rE3BPuj)

These are the boards that I am using to scratch build the revo in my first pic which follow the original OP Gerber. (http://imagizer.imageshack.us/v2/1024x768q90/633/d4NSVu.jpg) (https://imageshack.com/i/hld4NSVuj)
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: ggrif on November 29, 2015, 05:44:58 pm
Excellent information/work! Thanks!
I'm looking forward to following your quest.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: Brian on November 29, 2015, 05:57:27 pm
I just received one of the "modified" clone Revos, and your assessment is similar to my experience.  The clone seems to work fine, but it does have a different layout.

The only problem that I've found so far is that the power LED is closer to the mounting hole, so it interferes with standard (1/4" 4/40) nylon standoffs.  You can clearly see the difference in the picture above.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: TheOtherCliff on November 30, 2015, 07:37:19 am
...
The point is both of the different types of clones use the exact same 400mA LDO regulators and have 10uF caps on the baros VCC side. So that rules out a difference in regulators/caps for the revo clones.

It's my understanding that the problem is with the Bypass cap, not the Vout cap.  It oscillates if the value is too large.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: perchybits on November 30, 2015, 10:09:31 pm
Just thought i would chime in and add my experience to the discussion. I purchased the Amazon Revolution clone with the case and the yellow red black upright pins. Quality of the part looked good to the naked eye. Board was installed with a Ublox M8n GPS hooked to th eflexi port. After hours of messing with it I can confirm that mine not only has the bad barometer which makes altitude hold useless, and the Main port is not functioning at all. Board also is unusable in gps assist mode. It is impossible to calibrate in ins13 mode.  even with 20 satellites locked it dances and horizon falls and dips by 20-30%! I managed to get it up in the air in ins13 in rate mode and put the hexcopter into gps assist and altitude hold and it was hilarious to watch, the poor thing looked like it had cerebral palsy. It was shaking and dancing all over the place. So I removed all gps flight modes and turned basic mode back on.

Still... in Basic complementary mode it is super solid and flys like a champ! it is very smooth and fun to fly in Rattitude and rate settings.

i didn't have problems with the onboard mag. i t seemed to work fine. it would go to orange on full throttle but hold green most of the time.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: JaeMelo on November 30, 2015, 11:56:08 pm
It's my understanding that the problem is with the Bypass cap, not the Vout cap.  It oscillates if the value is too large.
Can you identify this cap you speak of in the schematic below?
Hi-Res Image (http://imageshack.com/a/img907/293/IdIA9A.png)

Just thought i would chime in and add my experience to the discussion. I purchased the Amazon Revolution clone with the case and the yellow red black upright pins. Quality of the part looked good to the naked eye. Board was installed with a Ublox M8n GPS hooked to th eflexi port. After hours of messing with it I can confirm that mine not only has the bad barometer which makes altitude hold useless, and the Main port is not functioning at all. Board also is unusable in gps assist mode. It is impossible to calibrate in ins13 mode.  even with 20 satellites locked it dances and horizon falls and dips by 20-30%! I managed to get it up in the air in ins13 in rate mode and put the hexcopter into gps assist and altitude hold and it was hilarious to watch, the poor thing looked like it had cerebral palsy. It was shaking and dancing all over the place. So I removed all gps flight modes and turned basic mode back on.

Still... in Basic complementary mode it is super solid and flys like a champ! it is very smooth and fun to fly in Rattitude and rate settings.

i didn't have problems with the onboard mag. i t seemed to work fine. it would go to orange on full throttle but hold green most of the time.
Nothing about that board is of quality not even from the naked eye.
In addition the behavior you mentioned is normal when you try flying with mag interference in any GPS mode. It happens with the real Revo's, Naze32's, sparky2 boards ect. The only way around that is to either build your multi rotor to be interference friendly around the FC or, to use a gps with a built in mag and configure the fc utilize the external mag instead. The gps must also be positioned as far away from the interference as possible on a post. If your mag turns anything but green you have an interference issue especially during throttle actuation.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: TheOtherCliff on December 01, 2015, 12:10:29 am
Just thought i would chime in and add my experience to the discussion. I purchased the Amazon Revolution clone with the case and the yellow red black upright pins. Quality of the part looked good to the naked eye. Board was installed with a Ublox M8n GPS hooked to th eflexi port. After hours of messing with it I can confirm that mine not only has the bad barometer which makes altitude hold useless, and the Main port is not functioning at all. Board also is unusable in gps assist mode. It is impossible to calibrate in ins13 mode.  even with 20 satellites locked it dances and horizon falls and dips by 20-30%! I managed to get it up in the air in ins13 in rate mode and put the hexcopter into gps assist and altitude hold and it was hilarious to watch, the poor thing looked like it had cerebral palsy. It was shaking and dancing all over the place. So I removed all gps flight modes and turned basic mode back on.

Still... in Basic complementary mode it is super solid and flys like a champ! it is very smooth and fun to fly in Rattitude and rate settings.

i didn't have problems with the onboard mag. i t seemed to work fine. it would go to orange on full throttle but hold green most of the time.

It seems that baro can maybe be fixed by removing a tiny capacitor.

A friend got a Revo board with a bad main port and I fixed it by looking at main port circuitry.  There was a short in the small filter chip that could only be seen with a jeweler's loupe.

PFD moving a lot is usually bad mags.  That can be bad mag calibration (little known is that calibration is happening all the time, not just when you push the button.  You must not set it down or close to anything bad the whole time you are calibrating.  It can be bad wiring, but that usually only shows up when the motors are under hard flight load (props on).
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: TheOtherCliff on December 01, 2015, 12:15:54 am
It's my understanding that the problem is with the Bypass cap, not the Vout cap.  It oscillates if the value is too large.
Can you identify this cap you speak of in the schematic below?
Hi-Res Image (http://imageshack.com/a/img907/293/IdIA9A.png)

C9 from pin 4 to ground is the important one.  Remove it and test again and let us know.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: JaeMelo on December 01, 2015, 05:44:14 am
C9 from pin 4 to ground is the important one.  Remove it and test again and let us know.

Removing that made things even worse. The altitude kept on increasing. I replaced that part with a brand new cap from spares and that didn't change a thing either.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: TheOtherCliff on December 01, 2015, 06:40:38 am
How much did it increase?  It should stop and level out after 5 or 10 minutes.
Did you use a 10nf when you put it back?  It depends on the type of regulator.
Also, I am extrapolating from a successful fix of a Sparky 2.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: Mateusz on December 01, 2015, 08:26:42 am
C9 from pin 4 to ground is the important one.  Remove it and test again and let us know.

Removing that made things even worse. The altitude kept on increasing. I replaced that part with a brand new cap from spares and that didn't change a thing either.

I would suggest to let it stabilize for a couple of minutes, when I turn my original Sparky2, altitude also increases at the beginning, baro must warm up. But the increases are getting smaller with a time and up to the point it stabilizes itself and measures altitude accurately.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: JaeMelo on December 01, 2015, 08:18:21 pm
How much did it increase?  It should stop and level out after 5 or 10 minutes.
Did you use a 10nf when you put it back?  It depends on the type of regulator.
Also, I am extrapolating from a successful fix of a Sparky 2.

At first there was a 10nf cap and it was jumpy like usually and also slow to altitude changes. Once I removed the cap. the altitude started to climb up to 35meters at that point I just unplugged it so it had to been less than 5mins. I replaced the old cap with a brand new 10nf cap and it went back to how it originally was. Jumpy but a lot better then the constant climbing that I experienced removing it.

I would suggest to let it stabilize for a couple of minutes, when I turn my original Sparky2, altitude also increases at the beginning, baro must warm up. But the increases are getting smaller with a time and up to the point it stabilizes itself and measures altitude accurately.

35meters seems like a long increase. Even if this did eventually stabilize this wouldn't be a satisfactory fix for myself. I Really wish these cloners would just use the correct damn components lol. I honestly might just have to replace every piece from the regulator forward on the baro circuit one by one till I find the problem.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: ggrif on December 04, 2015, 04:45:04 pm
FYI, just received a second Revo clone from Banggood's US store, all sensors bench test good.

Finally got the first one in a frame with V9 GPS, hope to do a bit of flying this weekend to check functionality.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: whirlygigg on December 16, 2015, 07:10:08 am
I bought two of these cloned Revos. One was from hobby king, the other came from a seller on amazon called hobby ace.

I think the baro is OK. The widget for barometer pressure varries .012 on both boards at room temperature. If I understand tbis thread correctly, that iz within tolerance.

I have not flown outside yet, but I did hover quite nicely in front of my cat's toilet for a while.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: TheOtherCliff on December 18, 2015, 10:18:08 pm
.012 kPa pressure noise sounds like a good board.  :)
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: soulreaper on December 22, 2015, 05:41:55 am
Glad i read this post.   Really dissapointed.  I currently fly a cc3d without any issues.  Was looking forward to getting the revo.   Does anyone sell a good revo?   Will some one eventually sell a good revo? 
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: ggrif on December 22, 2015, 07:17:41 am
Several "good" Revo's (clones) are referenced in this thread and elsewhere in this forum. Take your pick.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: Joe_D on December 22, 2015, 01:29:03 pm
Hello,
I bought a Revo clone from Fisher Hobby on Ebay, the baro error was in the +/- 3m range. Then I added a 10uF capacitor on the C29 capacitor  just beside the pressure sensor. The error is now within +/- 0.6m. Attached is a video showing how stable my tricopter is hovering in velocityroam mode.
Joe
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: TheOtherCliff on December 23, 2015, 09:49:53 pm
Excellent news on another way to fix a bad baro!

I am pretty sure that I have heard of both good and bad baros from at least one seller.  I have also seen two versions of the Revo being sold with very slightly different layouts; in particular, one has a component so close to a mounting hole that it interferes with a standard M3 nut or standoff.

I personally have seen a bad baro on a Revo from Thanksbuyer and on a Sparky2 from Goodluckbuy.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: sprockett on January 01, 2016, 12:55:11 pm
Im getting 40-80pa swing, can anyone show me where the C9 capacitor is on the board
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: f5soh on January 01, 2016, 04:51:27 pm
Look at assembly layout:
https://bitbucket.org/librepilot/librepilot/raw/cefcacbbcf7d7fbfa27aaf13c0bae909562ec869/hardware/Production/OpenPilot%20Revolution/Assembly/Revolution%20Assembly.pdf (https://bitbucket.org/librepilot/librepilot/raw/cefcacbbcf7d7fbfa27aaf13c0bae909562ec869/hardware/Production/OpenPilot%20Revolution/Assembly/Revolution%20Assembly.pdf)

Also schematic:
https://bitbucket.org/librepilot/librepilot/raw/cefcacbbcf7d7fbfa27aaf13c0bae909562ec869/hardware/Production/OpenPilot%20Revolution/Revolution%20Schematic.pdf (https://bitbucket.org/librepilot/librepilot/raw/cefcacbbcf7d7fbfa27aaf13c0bae909562ec869/hardware/Production/OpenPilot%20Revolution/Revolution%20Schematic.pdf)

C9 is a bypass capacitor on pin4 of regulator.
(https://forum.librepilot.org/index.php?action=dlattach;topic=311.0;attach=986)
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: lysie on January 04, 2016, 04:45:24 pm
Received a Sparky 2 today from banggood.. sadly baro altitude oscillates by +-5m - meh :/

I already send an email to banggood. Let´s see how they respond. It will be a mostly acro flying quad anyway but would have been nice to test the occasional gps mode. Best bet is probably to replace the voltage regulator but my soldering equipment isn´t quite up to that task.

Ah and the 3,3 / 5V toggle pads for the receiver port where bridged with resistors lol. I removed both of them and then bridged the 5V pad again with solder.

(http://i.imgur.com/VJs5X88.jpg)
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: f5soh on January 04, 2016, 06:02:21 pm
Looks like they replaced the original Reg with this one:
www.micrel.com/_PDF/mic5219.pdf

So the C8 cap is not the right value anymore. Try removing or replace with a 470pF.
Code: [Select]
C BYP is an optional, external bypass capacitor connected to devices with a BYP (bypass)(https://forum.librepilot.org/index.php?action=dlattach;topic=311.0;attach=1014)
If success i will update Wiki with your pics :)
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: TheOtherCliff on January 04, 2016, 10:46:10 pm
Waiting on your results with great interest.  My Sparky2 clone regulator is also marked LG33

Does LG33 clearly show (within reasonable limits of course) it is the brand / model that needs the 470pf cap?  Previously I had guessed that LG33 wasn't enough to identify the brand / model of regulator other than 3.3v.  :)
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: hwh on January 04, 2016, 11:59:12 pm
It's supposed to.  With the number of different manufacturers, number of SMD chips they make, short length code that will fit, and lack of a central registry there are duplicates. However I've never come across a duplicate that was the same package as the other chip with the same marking. 

This one, LG33, comes up easy in a google search but many of the codes are hard to cross reference.  While there are a couple of sites that have tried to collect codes in one place most of the time the only place the code is shown is in small print on the manufacturer's datasheet.  And google searches often can't find them.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: TheOtherCliff on January 05, 2016, 09:30:29 am
That's good news because it shows where my baro noise problem comes from.  :)
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: lysie on January 06, 2016, 12:38:30 pm
Ok guys, i have awesome news to report. It is definitely due to the cap.
Since i haven´t heard from banggood yet, i said fu** it and just remove the damn cap.

(http://i.imgur.com/rbGhsLT.png)

This is the result :)
Now i´m happy. Hope it will run fine without it.
It was hard enough the unsolder the damn thing.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: f5soh on January 06, 2016, 04:07:00 pm
Good news  :D
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: @marc on January 11, 2016, 10:17:55 pm
Hi!

Looks like I have the same problem.
 (https://forum.librepilot.org/index.php?action=dlattach;topic=311.0;attach=1100;image)

I bought this package from RCMaster: http://www.rcmaster.net/de-openpilot-cc3d-revolution-flugkontroller-mit-neo-7n-gps-und-power-distribution-board-interne-433mhz-p239545.htm
(http://rcmaster.net/desc/HR/HR1365/HR1365_4.jpg)

Is there anything someone with, let's say, very basic soldering skills can do about it?

Best Regards,
Marc
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: f5soh on January 11, 2016, 11:21:55 pm
For Revo try removing the C9 capacitor
Take a look here:
https://librepilot.atlassian.net/wiki/display/LPDOC/Altitude+Hold#AltitudeHold-Hardwareissues
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: @marc on January 12, 2016, 05:49:22 am
"Remove" means I should just cut the connection, or should I short curcuit it?
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: hwh on January 12, 2016, 06:43:46 am
Remove as in cut the connection.  I don't think the regulator would work if you shorted it.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: @marc on January 12, 2016, 08:58:35 am
Ok, will try this evening and report back.
Cut/Remove  C9, as in this pic.  ???

(https://librepilot.atlassian.net/wiki/download/thumbnails/12058671/Reg_ana_revo_original.png?version=1&modificationDate=1451781492234&api=v2)
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: TheOtherCliff on January 12, 2016, 02:44:43 pm
If you have a small soldering iron, good eyes (or a magnifier), and reasonable soldering skills, you should be able to heat up the whole tiny component and quickly unsolder it / remove it.  That way you still have the component to put back if necessary (don't sneeze :) ).  If unsoldering, you must make sure you don't leave a solder bridge across the two very close and tiny solder pads.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: @marc on January 12, 2016, 03:46:20 pm
Thanks for the tipp. I have good eyes and a magnifying glass. As for the soldering skills... well.

My idea was to cut one connection with an exacto knife, but heating up the whole component sound like a better idea. However, I don't know if my soldering iron is small enough.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: f5soh on January 12, 2016, 05:55:36 pm
Just need a normal iron and heat the two pads at same time.
Or use a hammer and explode the C9 capacitor.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: @marc on January 12, 2016, 06:44:11 pm
After seeing how small the thing is, I used the knife.

C9 is gone, Baro is exact!

(https://forum.librepilot.org/index.php?action=dlattach;topic=311.0;attach=1106;image)

Thanks, you guys are great!

(on a related note: it says I am ~160m high, but I am about 20m high... is there a calibration process for the baro?)
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: f5soh on January 12, 2016, 07:06:13 pm
No calibration, calc assumes pressure is 1023.5hPa at sea level so altitude measured can change to one day to another.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: TheOtherCliff on January 12, 2016, 11:43:43 pm
No problem because all calculations are relative to where the mode was switched on.

If it measures the ground to be at 160 meters and you say go up 1 meter it goes to 161.  If it measures 20 it goes to 21.  Both are 1 meter above the real ground.  It can even change from day to day if a big weather front is close.  The secret is that it just gets the current baro altitude when you switch into that mode and everything is relative to that.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: Xviews on January 13, 2016, 04:46:29 pm
Hallo, This is the my result, buy from banggood
is it good?
(https://forum.librepilot.org/index.php?action=dlattach;topic=311.0;attach=1119;image)
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: Mateusz on January 13, 2016, 05:22:28 pm
Hallo, This is the my result, buy from banggood
is it good?

To me it looks ok, but every baro might be a little bit different, due to factory calibration, small difference in caps etc.. You can read this thread and compare to what other people have.
For example this is my Baro [altitude] the red line corresponds to lowering original revo nano by exactly 58cm.

So you get the idea that baro is accurate (like specs says to 10cm), that means it should react on change in altitude by 10cm. Accuracy however says nothing about precision.
You can have values 100, 100, 100, 100 where the true value is 98, that would mean good precision but poor accuracy.
You can have values 98, 99, 98, 97 where again true value is 98, that would more or less suggest better accuracy, but more randomes in measurements so less precision.
 
Baros are quite accurate up to 10cm, but they're not very precise.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: TheOtherCliff on January 15, 2016, 12:58:15 am
@Xviews that one should do just fine.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: jobybett on January 15, 2016, 07:27:48 am
Just for my Revo from bulkdogs on ebay, seems like I got a good one!! Came with case and a bit of mic foam over the baros

See attachment sorry not worked out images yet
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: TheOtherCliff on January 15, 2016, 04:04:26 pm
That looks good too.  I figure that any FC that has about +-0.5 meters of baro noise (1m total variation) over several cycles of noise is OK.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: lysie on February 02, 2016, 01:16:43 pm
Just a quick heads up
http://www.xt-xinte.com/F16821.html
From the photos they seem to be using the correct regulator now.. but still bridged the 5V toggle pad with a resistor :D .
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: hwh on February 02, 2016, 03:41:45 pm
Bridging the toggle pad with a 0 ohm resistor is standard engineering practice for boards assembled by machine.  Normally the second pad set's "resistor" is specified as DNP (do not place) and left open.  Only boards hand assembled would normally have solder bridging them. 
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: FlyGuy on February 02, 2016, 09:16:58 pm
Is there anyway to physically tell if the Revo board purchased is a genuine open pilot board or an aftermarket clone?
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: hwh on February 03, 2016, 12:32:26 am
If you're buying it new then it's almost certainly a clone.  The only "genuine" revos are used ones being sold by the original purchaser.  It's been quite a while since any "genuine" revos were manufactured and it's rare to find anyone who has one selling it.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: suzali on February 04, 2016, 04:15:19 pm
Got my new revo clone from Aliexpress today. The one with the german color pins.
After calibrating the first thing i did was to check the baro. Here is the result.
What do the experts say?
 
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: Mateusz on February 04, 2016, 04:27:57 pm
Got my new revo clone from Aliexpress today. The one with the german color pins.
After calibrating the first thing i did was to check the baro. Here is the result.
What do the experts say?

Looks good to me, you can compare it to previous posts. Variation within ~1m is fine. I had spikes up to 9m with bad regulator :)
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: WashirePie on February 04, 2016, 05:36:07 pm
I got mine from banggood aswell. Its Baro seems to be pretty precise with an average error value of around .6m.

I'd say that's not too bad.

Still got some problems with the GPS Flightmodes, but that'a another topic.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: TheOtherCliff on February 04, 2016, 11:36:26 pm
Bridging the toggle pad with a 0 ohm resistor is standard engineering practice for boards assembled by machine.  Normally the second pad set's "resistor" is specified as DNP (do not place) and left open.  Only boards hand assembled would normally have solder bridging them.

I haven't used it yet, but I just measured the factory shunt (that is supposed to give full power from the ESC servo connector to the RC receiver) on my clone Sparky2, and it is 1k!  Yet another cloner problem.  I guess it is common for the cloners to just sweep the floor and use whatever they sweep up.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: TheOtherCliff on February 04, 2016, 11:49:31 pm
Just a quick heads up
http://www.xt-xinte.com/F16821.html
From the photos they seem to be using the correct regulator now.. but still bridged the 5V toggle pad with a resistor :D .

I have heard of good and bad regulators shipped from the same seller.  I would not trust any of them to ship a correctly made board.  Always assume there is something wrong with it and fully test it as soon as you get it.  Make the ones that produce bad boards regret doing it and maybe some year the boards will be better, in the mean time, you will save yourself some money by getting your money back or a reship of a good board.

Also, always pay with a method that allows you to get your money back from a bad seller.  I used to think that PayPal was the best for this, but lately PayPal is not so good.  Thanksbuyer.com shipped the wrong item.  They wouldn't admit it even after posting two sets of pictures.  I had to get PayPal involved and the only reason I didn't have to pay return shipping on wrong item sent, just to get a refund was that PayPal had a "special offer" to handle it for free for a few months around Christmas.  Read that "don't expect that in the future".
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: hwh on February 05, 2016, 12:03:52 am
I haven't used it yet, but I just measured the factory shunt (that is supposed to give full power from the ESC servo connector to the RC receiver) on my clone Sparky2, and it is 1k!  Yet another cloner problem.  I guess it is common for the cloners to just sweep the floor and use whatever they sweep up.

It's almost hard to blame the Chinese cloner for that one, the Tau BOM lists them as either NP or 10k.  I'm surprised they didn't populate both the jumpers, R15 and R17.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: onecooler on February 09, 2016, 05:19:18 pm
Hi All!

I have purchased a Revo clone from eBay a couple of weeks ago and now having problems in AltitudeVario mode. What I have done only one test so far (due to bad weather), but it makes me worry about baro. The altitude graph looks to be within 1 +- meter, but when I enable altitudevario  flight mode, quad starts gaining altitude intermittently. It looks like someone giving it a full throttle for a half of a second then hover for the same time and then it starts over again. Is it a baro issue or it is something I have missed during software setup?

Thanks in advance!
-K.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: Drifter on February 19, 2016, 09:55:45 am
Gday onecooler, not sure if you are aware or not but the baro needs to be covered with a piece of foam, preferably a dark colour, to shield it from sunlight which will cause the symptoms you mention.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: onecooler on February 19, 2016, 10:31:26 am
Gday onecooler, not sure if you are aware or not but the baro needs to be covered with a piece of foam, preferably a dark colour, to shield it from sunlight which will cause the symptoms you mention.

Gday to you too and thanks for the answer. I have a Chinese clone that has already been packed in plastic case. Inside of the case seller already put a dark piece of foam. However I have not opened the case and did not check how accurate it is covered. I think to disassemble it and revisit now.
Thanks.
-K.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: darkdave on April 18, 2016, 04:55:42 pm
My Revo is already encased in plastic. Is that good enough? I had the same problem with altitude holding not working properly and the drone jumped up and down. But the drone was flying under very cloudy grey skies and there wasn't much sunlight at all.

Are you sure the problem is sunlight? If I fly it at night will the problem go away? I had the same problem flying the drone in doors and the drone hit the ceiling and fell back down on the ground.

No sunlight there!

Last question: What if I bought an openpilot mini clone? Would that solve the problem? Or does the mini clones also have bad barometers?
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: f5soh on April 18, 2016, 05:27:42 pm
Baros are fine, just regulator that use same capacitor as original design but they changed the regulator.
https://librepilot.atlassian.net/wiki/display/LPDOC/Altitude+Hold#AltitudeHold-Hardwareissues

I don't know OpenPilot Mini, whats that ?
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: Mateusz on April 18, 2016, 05:32:58 pm
Are you sure the problem is sunlight? If I fly it at night will the problem go away? I had the same problem flying the drone in doors and the drone hit the ceiling and fell back down on the ground.

There can be many reasons (bad regulator, bad sponge, light, PIDs).
More powerful quad might require different altitude hold PIDs, than less powerful one. You should look into tuning those PIDs. They are called Vertical Velocity PIDs and can be found in GCS -> Configure -> Stabilization -> Altitude Hold
Try decreasing Altitude Proportional from 70 to 20, and Velocity Integral from 100 to 20, or play with those values. That that resolve the issue of jumps and downs ?
For me that helped, however making those values too low will cause that quadcopter will hold altitude well if no input but drop slightly when you move it. So you need to flatten throttle curve in the middle to get smoother 50% and play with values to find the sweet spot that works for you.
Those PIDs are not the same as stabilization PIDs.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: darkdave on April 18, 2016, 06:02:50 pm
Thanks for this advice, I have made the changes and will try flying my drone in the park tomorrow morning to test results.

Hopefully you were right that this six engine RD290 requires different PIDs vs QAV quadcopter.

If not I will have to research the possibility of buying a high quality external barometer for the revolution. Would this be an option too? Please let me know.

BTW, what does PID stand for?
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: Mateusz on April 18, 2016, 06:31:02 pm
Thanks for this advice, I have made the changes and will try flying my drone in the park tomorrow morning to test results.

Hopefully you were right that this six engine RD290 requires different PIDs vs QAV quadcopter.

If not I will have to research the possibility of buying a high quality external barometer for the revolution. Would this be an option too? Please let me know.

BTW, what does PID stand for?

PIDs is a controller and stands for Proportional Derivative Integral. You can search literature on PIDs controllers, but in general those are loops that you feed with input variable and they control something for example motors to reach desired value as quickly as possible without overshooting (really vague explanation, but I hope it makes it clear what's the purpose). Motors must affect input which could be sensor measurement and the feedback loop is closed. So for Altitude it is used to maintain height, for Stabilization it is used to maintain level.

As for the barometer, unless something new appeared on the market, the one used in Revolution is high precision and best for the purpose on the market. You will not be able to find anything better. It's just technological limitation.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: darkdave on April 20, 2016, 03:56:31 pm
I adjusted the PIDs and altitude Vario works fine now but Altitude Hold still fluctuates.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: TheOtherCliff on April 20, 2016, 05:46:32 pm
When the throttle stick is in the center, +-10% (the center 1/5th of travel) then ALtitudeVario becomes exactly ALtitudeHold.

There is a PID for vertical Velocity that is used when AV is outside the throttle center deadband.  There is a P that is additionally used for ALtitude/Position when in AH.  These are cascaded PIDs exactly like the stabilization Inner and Outer loop PID and PI used by ATtitude mode.

I have a weak 500 quad with Revo or Sparky2 that tunes AV/AH fairly well.  I have a weak (2s) or strong (3s) 330 quad with Nano that I can't seem to be able to tune for really tight lock.  Others with 250 class quads are also having problems with getting a good lock.  I am coding sonar support and it needs a tight lock to follow the ground accurately.  I'm investigating this and hope to get it much more solid.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: nacholibre on April 25, 2016, 04:26:51 am
thats how mine does. really cant use the gps functions. always going back and forth with no baro or mag signal and fly's like a drunk mosquito in  gps mode. if i disable the gps and fly in comp mode i have very few problems at all. if i want to fly that model i always have to hook it to the laptop and go through the whole calibration thing every time. it take so long i just don't fly it much. and never in gps mode. thats why i bought it. and ive never once got to use a gps mode. which i must say makes me mad put as nice as i can say it. how do i know who to get an official one from. mine i bought on amazon but it came from so Chinese company so who knows? it cost me alot more than the cc3ds i had been buying and more than the skyline naz 32 i bought so i thought this one has to be good. who are the reputable sellers?
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: hugges on April 27, 2016, 05:47:03 pm
Hi i have just received  a replacement revolution  from banggood i have included a screen shot
can some one tell me if the baro is good or bad
Its not fitted into the quodcopter  yet just plugged into pc
any help
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: f5soh on April 27, 2016, 06:07:10 pm
Looks ok, keep in mind this is raw data from Baro sensor without filtering.

(Moved to the appropriate thread)
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: hugges on April 27, 2016, 06:21:22 pm
Thank you but what do you mean with out filtering ,where will the filtering come from
Sorry i am  new to this copter building
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: f5soh on April 27, 2016, 06:33:07 pm
The filtering allow removing the spikes.
The BaroSensor.Altitude is raw from sensor, just computed altitude using the pressure measured.

This data is filtered later in the process.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: MGR17 on May 06, 2016, 04:00:14 pm
Hi, I have just found this excellent forum and hope you can help.

with the Revo static my barometer is showing 3m with a 0.6m variation, however it hardly registers pressure change at all ie possibly 0.5 metre change for 4 metre actual change in height.  Also the vertical speed indicator does not move when the Revo is raised/lowered.  I have opened the plastic case, removed the foam and blown on it and again no change. My question therefore is removing D9 likely to help or is that just to reduce fluctuations.
I have also been trying the GPS functions with little success and wondered if  they need a working barometer to function.
I have moved the Revo away from power lines and the magnetometer traces remain  steady when full power is applied satellite reception also appears good.

Any suggestions would be much appreciated.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: f5soh on May 06, 2016, 04:38:14 pm
Hi, welcome.

Whats "D9" ?
The issue you can see with regulator is quick changes / jumps.
value that oscillate within 0.6m is fine.

For long / slow changes in altitude this can be related to weather change or thermal drift.
You can minimize the thermal drift effect doing the thermal calibration.

https://librepilot.atlassian.net/wiki/display/LPDOC/Sensor+calibration#Sensorcalibration-Thermalcalibration
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: nuggetz on May 06, 2016, 05:23:01 pm
Does anyone have whatever files one would need to have a proper Revo made at one of those online pcb manufacturing places? Not sure what the proper terminology is. I love this platform and it's a shame that there are no quality boards available. I may just go the Pixhawk route if this isn't possible.


Sent from my iPhone using Tapatalk
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: hwh on May 06, 2016, 05:49:27 pm
https://bitbucket.org/librepilot/librepilot/src/b00ac8a55a93e022e8e8d0fb469c23c33a7ed266/hardware/Production/OpenPilot%20Revolution/?at=next (https://bitbucket.org/librepilot/librepilot/src/b00ac8a55a93e022e8e8d0fb469c23c33a7ed266/hardware/Production/OpenPilot%20Revolution/?at=next) has all the design files.  You can order the blank boards from https://oshpark.com/shared_projects/8Dz8BT1f (https://oshpark.com/shared_projects/8Dz8BT1f)
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: MGR17 on May 06, 2016, 06:13:49 pm
Apologies I mis-typed it should have read C9. My barometer does not seem to register changes in altitude/pressure, has anyone else experienced/overcome this problem?
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: hwh on May 06, 2016, 10:26:06 pm
...My question therefore is removing D9 likely to help or is that just to reduce fluctuations.
I have also been trying the GPS functions with little success and wondered if  they need a working barometer to function....

Removing C9 just fixes the problem of the barometer varying too much, it wouldn't do any good for the barometer not working at all.

Your description of "with little success" doesn't really give enough info on what problem you're having to suggest anything.  A little detail on what it's doing or not doing would help.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: MGR17 on May 07, 2016, 03:13:44 pm
When placed in position hold  or RTH the quad just fly's off and I have to revert to non GPS mode. I there fore wondered if having s unchangingly barometer could be the cause.  The only other possibly unusual thing I am doing is that I set my home locatation at my house calibrate everything but then go 3 miles to my flying field. I have also tried checking the home location not set  box before proceeding to the flying field. Both approaches result in attempted flyaways
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: Mateusz on May 07, 2016, 09:30:06 pm
Both approaches result in attempted flyaways

Is your external magnetometer (AuxMag) calibrated and always green ? Does model react up/down/right/left correct in GCS model view ? Is model stable when in reset or when motors are running but not yet in the air ? Might be magnetic interference to magnetometer or bad mag calibration. No oscillations in EKF (Atitude states with INS31) ?
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: TheOtherCliff on May 07, 2016, 09:48:24 pm
Quad will not arm in EKF unless Home is set.

Also Home and Base are two different things used for different purposes.

Home is used for GPS coordinates.  When using EKF, the coordinates are relative to Home.

Base is just where it returns to when you do RTB.  The default for Base is that it is set each time you arm a new battery (once GPS gets a good fix).

Home should be set "close to where you fly" but doesn't generally hurt anything if not.  Example:  If my Home is set to flying field (50km away) and I fly EKF at my house (50km away from where Home is set), my coordinates on the GCS map are off by several hundred meters, but it is all relative so it just doesn't matter.

It doesn't fly away if Home is a long way away, it just means that it thinks it is here when it is there.  For me it was 300m wrong when Home was 50k away.  It really only hurts if you are using waypoint flight, like trying to fly between trees on the map.  The map will be wrong (by e.g. 300m) and thus the trees will be hard to avoid.

PH flyaway (really this exact thing happens in any GPS mode) would usually be caused by bad mags or by GPS failure after takeoff.  One time it happened to me and I had a log, I researched it and found that the mags were bad at high power in the air.  Another time it happened to me because I couldn't get it to arm with my FPV switched on, so I switched FPV off, armed, then switched FPV back on, then flew (with a GPS signal that had gone bad).  I learned... :)

Your high current (motor) wiring MUST be twisted correctly and it is a good idea to test the mags at high motor power.  Make a log in a high power test flight that does not use EKF or GPS and make sure the mags stay green no matter what direction you fly.  Better yet, strap it down to your back porch, and watch the mag scope while you run the motors up to high power.  It should change very little (like 10% or less at full power).  This must be done with props on so there is a lot of current flow.  Be careful.

One way that might make it easier to "hold down" is to swap props so it pushes down instead of trying to lift off.  Take all props off and put them on (upside down if you like) the motor to the immediate CW (or CCW).

I wrote this quickly.  I hope it helps.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: MGR17 on May 08, 2016, 08:54:46 am
Many thanks for all your suggestions,  Just one point I am using  the internal magnetometer but have placed the Revo on the top plate of a qav250 away from the hhigh current wiring.  I had tried high throttle and the mag traces looked stable but I will try that again. 
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: Mateusz on May 08, 2016, 09:24:53 am
Many thanks for all your suggestions,  Just one point I am using  the internal magnetometer but have placed the Revo on the top plate of a qav250 away from the hhigh current wiring.  I had tried high throttle and the mag traces looked stable but I will try that again.

Are your power wires twisted ? Top plate of 250mm quad might not work, you need AuxMag and ~14-16cm mast for GPS navigation to work. Also it seems you already know at least one of your sensors is not working, and other gives noise. Why ignoring that is not so good idea I replied here https://forum.librepilot.org/index.php?topic=1512.msg11142#msg11142

To get better understanding I suggest reading this great post by Cliff https://forum.librepilot.org/index.php?topic=15.msg36#msg36
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: MGR17 on May 08, 2016, 11:40:38 pm
I think just need to get my barometer working as it fly's well in stabilised mode .  One thing I have noticed is that when I upgraded the firmware from open pilot to librepilot there was a yellow warning exclamation mark in the area to the right of the check some etc. Is this normal ?

In the meantime I will have to continue using my multiwii quad where  all the  GPS functions are working well with the internal magnetometer
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: markharper1989 on May 11, 2016, 08:53:47 am
This is my first post on the forum, I used to use CC3D a year or two ago but got back into flying and liked the look of the Revolution. Purchased from Banggood and received two weeks ago. All seems to work and flies steady in complementary mode apart from Altitudehold / Vario which show some signs of oscillations and generally unsteady. I have attached two plots of my scopes, please could you tell me if this is cceptable or if I have one of the faulty (low res baro / bad regulators) please?

Also I have tried adjusting the Altitude Hold PID settings but it does not cancel out the changes in altitude it just slows the quads reaction times, please could you try and help me get my quad working again?

Thanks!

Mark
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: TangoEchoAlpha on May 11, 2016, 07:49:38 pm
Just for reference for other people, here is the barometer scope from my Revolution board clone from Hobbyking.

The minimum kPa value is 101.787 and the maximum is 101.803 over a 3 minute period. No major, sudden fluctuations. In the flight data window, the altitude has gradually increased from -0.9 to -1.6 over a few minutes but no sudden fluctuations.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: TangoEchoAlpha on May 11, 2016, 07:52:00 pm
This is my first post on the forum, I used to use CC3D a year or two ago but got back into flying and liked the look of the Revolution. Purchased from Banggood and received two weeks ago. All seems to work and flies steady in complementary mode apart from Altitudehold / Vario which show some signs of oscillations and generally unsteady. I have attached two plots of my scopes, please could you tell me if this is cceptable or if I have one of the faulty (low res baro / bad regulators) please?

Also I have tried adjusting the Altitude Hold PID settings but it does not cancel out the changes in altitude it just slows the quads reaction times, please could you try and help me get my quad working again?

Thanks!

Mark


According to hwh in my thread, he said that "I usually think of it in terms of altitude variation where 1 to maybe 1.5 meters variation is reasonable."

https://forum.librepilot.org/index.php?topic=1364.15
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: markharper1989 on May 11, 2016, 08:28:06 pm
Thanks for your help, I take it that it is down to my pid settings that my quad won't hold altitude.

I have tried a number of settings some seem to improve the flight but not correct it fully.

The problem is as follows, the quad flies very well in normal attitude mode with manual thrust (mode 1 on my controller) then I flick to mode two (identical to mode 1 except thrust is altitude vario) when stable, centre the throttle and the quad will sometimes slowly loose altitude, sometimes slowly gain altitude but once or twice it has gained altitude fast (3 or 4m over a second), the quad does react to increasing or decreasing throttle when gaining or loosing altitude slowly but hardy reacts when gaining altitude fast (causing me to flip back to mode 1 to bring the quad back down to a more suitable height).

I'm at a loss what to try next, my quad is a 250 with 2204 motors and 5x3 props running 3s battery with revo controller (I have GPS but have disabled until I get the altitude sorted, then I'll sort out mag and only when they are both solid will I attempt gps). I have foam over the baro and have looked under a scope and it's the correct baro, please can anyone in the community suggest anything or share there setup if it's a similar quad?

Thanks for any help!

Mark
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: TangoEchoAlpha on May 12, 2016, 01:40:53 am
Thanks for your help, I take it that it is down to my pid settings that my quad won't hold altitude.

I have tried a number of settings some seem to improve the flight but not correct it fully.

The problem is as follows, the quad flies very well in normal attitude mode with manual thrust (mode 1 on my controller) then I flick to mode two (identical to mode 1 except thrust is altitude vario) when stable, centre the throttle and the quad will sometimes slowly loose altitude, sometimes slowly gain altitude but once or twice it has gained altitude fast (3 or 4m over a second), the quad does react to increasing or decreasing throttle when gaining or loosing altitude slowly but hardy reacts when gaining altitude fast (causing me to flip back to mode 1 to bring the quad back down to a more suitable height).

I'm at a loss what to try next, my quad is a 250 with 2204 motors and 5x3 props running 3s battery with revo controller (I have GPS but have disabled until I get the altitude sorted, then I'll sort out mag and only when they are both solid will I attempt gps). I have foam over the baro and have looked under a scope and it's the correct baro, please can anyone in the community suggest anything or share there setup if it's a similar quad?

Thanks for any help!

Mark

If you are using the Librepilot GCS, note, while the quad is in mode two, how the altimeter's values change. If, for example, you set it to hold altitude but due to perhaps a barometer problem the barometer readings are changing to reflect increased a climb, then the quad will react to the non existent change by reacting with a descent in an attempt to get back to the altitude it should be holding.

One thing I might try would be to remove the propellers (so it won't change altitude), setting the quad down somewhere with the Openpilot board still wired in but also hooked up to your comp so you can see the GCS readings. Set the quad to any arbitrary RPM and set it to hold altitude. In the scopes, you should theoretically see a constant RPM because the quad should think its maintaining its current altitude with whatever RPM the motors are spinning with. If, however, the scope shows the altitude changing (though its not actually since the props are off and its on the ground), you should expect to see a RPM change in an attempt to go back to the altitude it thinks it should be at but already is at in actuality.

In reality, these barometers are not flawless and perhaps may not have the resolution to stay steady within a meter for example. So I'd say the main problem is how big are the fluctuations are. Secondly, you report that sometimes the quad's altitude suddenly changes while in flight. Well, when just the board is plugged into the computer so you can see the scope for the barometer, are there ever sudden fluctuations in the barometric readings?

I'm not familiar with Librepilot or quadcopters but these are really just my thoughts on the matter.

Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: darkdave on May 23, 2016, 02:53:28 pm
Quad will not arm in EKF unless Home is set.

Also Home and Base are two different things used for different purposes.

Home is used for GPS coordinates.  When using EKF, the coordinates are relative to Home.

Base is just where it returns to when you do RTB.  The default for Base is that it is set each time you arm a new battery (once GPS gets a good fix).

Home should be set "close to where you fly" but doesn't generally hurt anything if not.  Example:  If my Home is set to flying field (50km away) and I fly EKF at my house (50km away from where Home is set), my coordinates on the GCS map are off by several hundred meters, but it is all relative so it just doesn't matter.

It doesn't fly away if Home is a long way away, it just means that it thinks it is here when it is there.  For me it was 300m wrong when Home was 50k away.  It really only hurts if you are using waypoint flight, like trying to fly between trees on the map.  The map will be wrong (by e.g. 300m) and thus the trees will be hard to avoid.

PH flyaway (really this exact thing happens in any GPS mode) would usually be caused by bad mags or by GPS failure after takeoff.  One time it happened to me and I had a log, I researched it and found that the mags were bad at high power in the air.  Another time it happened to me because I couldn't get it to arm with my FPV switched on, so I switched FPV off, armed, then switched FPV back on, then flew (with a GPS signal that had gone bad).  I learned... :)

Your high current (motor) wiring MUST be twisted correctly and it is a good idea to test the mags at high motor power.  Make a log in a high power test flight that does not use EKF or GPS and make sure the mags stay green no matter what direction you fly.  Better yet, strap it down to your back porch, and watch the mag scope while you run the motors up to high power.  It should change very little (like 10% or less at full power).  This must be done with props on so there is a lot of current flow.  Be careful.

One way that might make it easier to "hold down" is to swap props so it pushes down instead of trying to lift off.  Take all props off and put them on (upside down if you like) the motor to the immediate CW (or CCW).

I wrote this quickly.  I hope it helps.

What is "PH" in "PH fly away"?

This is by far the most useful forum thread I have read. I like to suggest the information and photos here be added to the librepilot wiki. Shall I do some copy pasting to it tonight?

Btw, why is your shirt always off in your picture? I always "feel strangely naked" when I read your posts.

Regards, David
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: darkdave on May 23, 2016, 06:05:48 pm
Ok, will try this evening and report back.
Cut/Remove  C9, as in this pic.  ???

(https://librepilot.atlassian.net/wiki/download/thumbnails/12058671/Reg_ana_revo_original.png?version=1&modificationDate=1451781492234&api=v2)

Please have a look at attached photo of my board. Is it the same board? Because to me it looks kinda different. Can you identify for me which is the "c9" that I need to heat up with a soldering iron and pull out like a dentist?

David
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: darkdave on May 23, 2016, 06:28:36 pm
Here's another close up with higher magnification.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: f5soh on May 23, 2016, 07:05:09 pm
Not the same board, that a redesigned Chinese clone
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: darkdave on May 24, 2016, 04:03:08 am
Can you guys find out what I must do to the redesigned version to get the same results?

The barometers are still too oscillating. Even after reducing altitude PIDs. I can mail one to you if you need.

David
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: Jhinta on May 25, 2016, 06:12:43 pm
Not the same board, that a redesigned Chinese clone

Is there eny info about that if they are good or not , also any alli link for 100% clone or any
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: darkdave on May 25, 2016, 06:48:04 pm
Not the same board, that a redesigned Chinese clone
Is there eny info about that if they are good or not , also any alli link for 100% clone or any

I found an electronic  supplier who understands the open pilot range of hardware and fault history. He can manufacture for my ebay account open pilot devices without the barometer and radio telemetry stability flaws. However there is still one flaw we don't know how to track down:

This is the flaw of a drone in fail safe mode being taken control by a remote again as its turned back on. In a propeller off test I set the fail safe channel to set all the axis to manual instead of stabalize so I can confirm on my table that the drone is indeed in failsafe mode by tilting it and checking if the engines stay at the same speed or try and stabalize by speeding up and slowing down. I then forced the drone into failsafe by turning off my remote controller and indeed the drone went into failsafe properly, the problem is what happens when I turn the controller back on: regardless of which channel im in the drone cuts all the engines for 2 seconds as the controller takes back control of the drone before the drone responds to my commands. This is 2 seconds of potential free fall time.

Has anyone else experienced this problem? I need your help to confirm if it's a prevelant problem or if it only happens to certain boards.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: f5soh on May 25, 2016, 07:21:02 pm
The failsafe lag you see has nothing related with the board you use.

I think that simply the lag from your RCTransmitter / transmitter module at power up.
Try disconnecting only the signal wire from the receiver instead.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: darkdave on May 25, 2016, 08:16:29 pm
OK I will... will keep you posted.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: hugges on June 22, 2016, 11:41:06 am
Hi im having problem with a revo and need to locate C9 cap thats near the regulator but where
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: f5soh on June 22, 2016, 11:51:36 am
You should locate the capacitor between pin4 from regulator and ground.

(https://librepilot.atlassian.net/wiki/download/attachments/12058671/revo_reg_sch.png)

(https://librepilot.atlassian.net/wiki/download/attachments/12058671/113NA.png)
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: Tomcatt on August 18, 2016, 02:31:23 am
Here's what I'm working with.  Maybe I can get in there and just the 4 pin on the regulator but I'd like to make sure that one on top is the one to cut.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: f5soh on August 18, 2016, 11:27:05 am
Yes, you should do the job on regulator found on top.
The one that power Accelerometer and Pressure sensor.
On back there is the regulator dedicated to power RFM22 module.

https://github.com/librepilot/LibrePilot/raw/next/hardware/Production/OpenPilot%20Revolution/Revolution%20Schematic.pdf
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: Brunosanta on September 28, 2016, 11:45:27 pm
guys you are genius.. I have just removed the c9 capacitor instead of 6 to 10 meters variation ( after calibration), I am getting like half to 1 meter.
If I want to include another correct capacitor what color would it be? anybody has a photo of the one? Considering that by putting the capacitor I will get a even better resolution!

thank you
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: f5soh on September 29, 2016, 12:00:08 am
If your regulator has a LG33 marking you can replace with a 470pF capacitor.
If you don't know have this capacitor value you can simply stay with capacitor removed like the datasheet says.

https://forum.librepilot.org/index.php?topic=311.msg3861#msg3861
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: Brunosanta on September 29, 2016, 12:10:58 am
I cant really find the color of the 470nf smd capacitor to go and hunt on my old eletronics. would you know the color of it? thank you F5soh
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: Brian on September 29, 2016, 12:33:04 am
That should be 470pF, not 470nF, and SMD capacitors are all pretty much a beige color.  You can't tell the value of them by looking at them.

Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: Brunosanta on September 29, 2016, 02:54:48 pm
Hello Brian, I have mistyped it.. I mean 470 pico fahrad.. thank you, so no chance for me to get a SMD one.
In between I have found a normal size one, in my electronics which is 473Pf, do you reckon I could use this one successfully, or it has to be the exact 470Pf in order to work with the LG voltage regulator?
Cheers.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: hwh on September 30, 2016, 02:17:15 am
The difference between 470pF and 473pF wouldn't make any difference.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: f5soh on September 30, 2016, 11:40:30 am
473pF is a weird value for a capacitor... is a measured value ?

If you have a SMD component with "473" on it, that more likelly a 47K resistor.

This capacitor is optional, better stay without compared to a bad component or value.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: Mateusz on September 30, 2016, 01:18:14 pm
473pF is a weird value for a capacitor... is a measured value ?

If you have a SMD component with "473" on it, that more likelly a 47K resistor.

This capacitor is optional, better stay without compared to a bad component or value.

Technically it's a possible value, but since pico is smaller than nano and probably it's within error range of batch reproducibility and with what you can measure with your capacitance meter, I doubt it could be incorrect. But 1m from lowest peak to highest peak (+-0.5m from average) is max what this type of sensor can give you.

This sensor has 12cm accuracy but precision is another thing (see attached picture) and that's to my knowledge best what you can get with digital barometers on the market. There is new one recently announced with 10cm accuracy but also as similar precision.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: Mateusz on September 30, 2016, 02:14:06 pm
Regarding correct capacitor

That should be 470pF, not 470nF, and SMD capacitors are all pretty much a beige color.  You can't tell the value of them by looking at them.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: anthropo on November 29, 2016, 09:23:10 pm
hello,
sorry but i have a doubt . I have this board, could someone  show me the capacitor to remove ?

(https://forum.librepilot.org/index.php?action=dlattach;topic=311.0;attach=3928;image)
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: QC102 on December 03, 2016, 06:04:38 am
I have two Revo boards from BangGood - I am clueless as to  their quality - still waiting for a gizmo to connect  my NEO M8N to the uBlox website - so they are not in use.
How do my boards stand as far as the Baro quality? 

Pix attached
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: TheOtherCliff on December 03, 2016, 07:01:11 am
That looks like a good one.  If you switch the scope to altitude (instead of pressure) you will see about +-0.5m of altitude noise.  That is more understandable to me.  And that +-0.5m will be smoothed out by the firmware.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: QC102 on December 03, 2016, 07:07:43 am
Thanks Cliff - I will  try that.
I added a screen grab of the other Revo (no pun intended) - I thought I had  included in post but seems not!
Nice to get some technology that  works well from BG...
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: anthropo on August 21, 2017, 06:50:48 pm
hello,

I have this results (altitude, in meters)  with this board

(https://forum.librepilot.org/index.php?action=dlattach;topic=311.0;attach=3928;image)

https://www.banggood.com/OpenPilot-CC3D-Revolution-Revo-10DOF-STM32F4-Flight-Controller-Staight-Pin-p-1000068.html

I suppose I have to remove the C9 capacitor but I don't know where the capacitor C9 is on this board

Can you help me please ?
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: anthropo on August 21, 2017, 07:32:03 pm
still searching. Seems that this regulator isn't the same ?
it's labelled R13c
https://www.google.fr/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwi7hbuy7OjVAhXDtRoKHeLwDOMQFggnMAA&url=http%3A%2F%2Fwww.ti.com%2Flit%2Fpdf%2FSBVS031&usg=AFQjCNFOIAxeSwhojRhFbUOYeDxwCTX9Ow
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: Mateusz on August 21, 2017, 09:54:13 pm
Hi anthropo

You should plot BaroSens.Altitude [m] where 'm' stands for units in meters, or kPh. Without units, not much can be said about plot.
Just compare your plot, with my earliest post https://forum.librepilot.org/index.php?topic=311.msg2157#msg2157

I only looked at BaroSensor.Altitude [m] on the left part of scope you can see Bad baro on the right part same scale you can see good baro after switching boards.
Bad baro (lowest 173.5, highest 182.5, difference 9 meters!)
Good baro (lowest 175.5, highest 177, difference 1.5 meter)

So bad baro is when you have more than 1.5 meter from most lowest peak to most highest peak. That is like +-0.75 (half of 1.5) from the average. This is in meters [m].

I cant help with capacitor, I identified it was faulty and send back Revo to seller immedietly, using my bayers protection from PayPal. If you don't send faulty product back, they might think it's ok to sell clones like this because no one complains.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: anthropo on August 21, 2017, 10:53:17 pm
Thank you. I have a bad baro.  5m at least. Nothing to do but change board ?
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: TheOtherCliff on August 22, 2017, 09:41:18 am
The problem is that manufacturer of this batch of Revo used cheaper, different spec part for voltage regulator.  Original regulator specified that it needs a large capacitor (large value, tiny physical size) for circuit #1, but replacement needs a smaller capacitor.  Replacement oscillates slowly if the capacitor is too large.

Solution is to completely remove large capacitor.  I have also heard that adding capacitance at the baro chip on circuit #2 (+3.3 to ground) will fix the issue.

#1 and #2 are just my titles to make it clear there are two different circuits, one where you remove capacitance and another where you add it.

There is a post in a thread that shows which to remove.  Some talk about C8 on Sparky2 board.
https://librepilot.atlassian.net/wiki/spaces/LPDOC/pages/12058671/Altitude+Hold#AltitudeHold-Hardwareissues
https://forum.librepilot.org/index.php?topic=311.msg2246;topicseen#msg2246
https://forum.librepilot.org/index.php?topic=311.msg3705;topicseen#msg3705
https://forum.librepilot.org/index.php?topic=311.msg13515;topicseen#msg13515
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: anthropo on August 23, 2017, 05:00:47 pm
I finally searched, found and removed the C9 capacitor on my chinese clone labelled Rev. C

for those with the same board the culprit is cercled in red

Much more better, but still sometimes peaks about 4 meters
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: TheOtherCliff on August 23, 2017, 07:53:02 pm
Those spikes look like something else.

I would install the desired 490pf at C9 if I had one and/or add some capacitance at the baro chip from ground to V+.
Title: Re: Warning: At least some sellers are selling Revos with bad baros
Post by: anthropo on August 23, 2017, 08:03:08 pm
I decided to use the 10nF capacitor to put over the C29 like described in this thread. Then it works !