[Rood_Dragon]

anyone had any experience using one of these on the revolution



http://www.ebay.com/itm/OP-GPS-for-Openpilot-CC3D-Revolution-EVO-Flight-Control-Atom-Mini-CC3D/252133496602?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D34227%26meid%3D02ed5409db6944c882507743348c1a7c%26pid%3D100005%26rk%3D4%26rkt%3D6%26sd%3D281802191710

[TheOtherCliff]

I don't personally, but two things I would warn against:
- small size small antenna reduced signal
- no mag.  if you want this, you probably want it for GPS flight on a mini quad and mini quads need an external mag even more than larger quads.

I would get the M8N for $22 (shipped) before the one you posted, but be aware that you must replace the connectors.  Also be aware that you can get one with OP connectors for maybe $10 more.
http://www.ebay.com/itm/251997592219

[Zrisst]

I have one of those.

Inside mine it's a M7N. No compass, as cliff said. Small, but poor in satellite reception.

I had a M8N, a mushroom type, like the one cliff said but without mag cables, and meanwhile I solve the mag wiring I decided to mount the one you shows (I think is the same, Aliexpress/Banggood) for reducing weight and to give it a try. In the same airfield with the big one (M8N) sit over a mast (http://www.tarot-rc.com/index.php?main_page=product_info&products_id=1259) got over 16 sats, very quick, very reliable. M7N mounted over the frame on one arm (a Tarot 250 quad) got 6 or 7. I haven't done deeper checks (I have read about differences between M7N and M8N but no real experience) but at first sight the small one looks like poor reception gain.

Apart of that, the communication with Revo was correct, no config problems.

In short words, it is compatible without troubles but less quality. If you are going to use autopilot and the big one fits in your frame I should get the one cliff says. for the money difference, it worth it.

[Rood_Dragon]

Thanks for the reply. good info  yes it is going on a smaller quad 320 frame and 250 frame. I have no problems changing the connectors but would like the link to the one with op connectors

[TheOtherCliff]

Thanks for the reply. good info  yes it is going on a smaller quad 320 frame and 250 frame. I have no problems changing the connectors but would like the link to the one with op connectors

Here is a GPS that supposedly comes with OP connectors.  It is large.  I can tell you that black and red are correct, so the power is right at least.  I have not bought one of these.  I don't recall hearing back from anyone having one yet.  If anyone has one and has tested both the GPS and mag connectors (aux mag is not released yet, so it requires pre-release version), please post here.
http://www.ebay.com/itm/NEO-M8N-M8N-8N-GPS-W-Compass-for-CC3D-Revolution-Flight-Controller-Better-7N-/121784646204

[RayRegan]

I have the small GPS receiver that was mentioned at the top also. I wanted to put it on my 250 so I could have a home arrow, altitude, and ground speed on my OSD. I was not able to get it to work. I read a lot of info on the web about how to enable the port and tried all the baud rates as well as the 2 different protocols. I have now ordered the larger receiver with the mag mentioned in this thread. I hope I can make that one work. Does anyone know if I need to use an FTDI adaptor to alter the firmware in anyway before use. I saw a video on YouTube where someone talked about doing that. When I tried it with the small receiver, a message popped up and said that that file was for a different receiver. It is also very hard to connect that tiny plug to and FTDI adaptor.

[TheOtherCliff]

The default settings for GPS in LP firmware will auto configure everything (including baud rate) for you and it will just work.  This is for a UBX GPS.  Ucenter (the UBX config app) must have the baud rate and port configured correctly to work.

To use the FTDI with a GPS the first thing you need to do is make that cable somehow.

If the GPS is plugged in, then looking at the connector from the wire looking toward the FC, ground (usually black) should be on the left and +5V (usually red) should be next.  If you have those two correct, you might consider swapping #3 and #4 around because GPS txd needs to connect to FC rxd, etc, and you may have it wrong.  Swapping 3 and 4 won't hurt it.  Use a strong magnifier to see the connector, and gently lift flaps and slide the pin out (the smallest lift possible that allows you to slide the pin out) for #3 and #4.  Re-insert as #4 and #3.

[RayRegan]

Thank you for the Info
I just read that the ports on the CC3D can be configured as a comm bridge. I wonder if that means I could use the CC3D as an adaptor to access the tiny GPS plug thru the CC3D. When I bought the board it also came with a plug that broke out into 4 single pin connectors( probably for additional peripherals)
that would work well in my FTDI adaptor. Unfortunately the auto-config feature does not work for CC3D, only for REVO. LP software says that firmware only supports UBLX protocol and not NEMA anymore, as it is too costly on memory. I have downloaded the U-center software and will try to configure the GPS using that.

Thanks Again   

[TheOtherCliff]

The minor issue with using Revo/CC3D as a USB to serial converter is that you must enable the ComBridge feature and reboot, and you must have the ComBridge baud rate set correctly (does not require a reboot, at least on Revo).  When you change the baud rate using Ucenter, you must also change the ComBridge baud rate.  I recall that in some conditions, it would make a new port when you changed the baud rate and the best way was to close the port in Ucenter before changing the ComBridge baud rate?

Anyway... you may have to fiddle with it, but it works.  I have done this using Revo at least.

[f5soh]

If you are using the same Gps like in the first post you can't use it with CC3D or you need to configure GPS every time.
Gps is small, cheap and uses only a couple of components without flash to store config.

With Revo, Gps is configured at start so no issue.

[TheOtherCliff]

Because of @f5soh's post, I went back and looked at the listing and saw that it doesn't save settings.  That does indeed make it unusable with CC3D unless you want to compile, test, and tweak your own CC3D firmware where you enable NMEA and disable UBX (GPS).

[hwh]

The one I ordered came in today.  Physically it's a little smaller than an oplink.

I plugged it into a revo and it autoconfigured and worked fine.  Came up 57600 and ubx protocol.  I put it and the revo out on my wooden picnic table so it would have a clear sky view and it took about 15 mins to get an initial fix.  At that point it could see 16 sats according to GCS but it was only using 6 of them.  It took it another 10 - 15 minutes before it finally started using 7 sats and GCS stopped complaining about the poor quality of the fix.  I went outside and power cycled it to see warm start performance and by the time I walked back inside it had a lock again.

A cc3d was another matter, I enabled the GPS module, set the port to 57600 and ubx proto, and power cycled the board.  It couldn't see the GPS when it came back up.  I tried various baud rates and both ubx and nema protocol but it never came up.  I wanted to tear the hardware apart so I didn't spend more than about 10 minutes trying.  This was with 15.09 release.

I then took it apart.  Both the cable strain relief and module are stuck to the case with a silicon sealant.  To save anyone else from having to unstick it and unsolder the rf shield I've attached pictures.  As the listing said, it has no flash to save configuration.  It does have a small battery, so it does warm start OK.  Looking under the rf shield it appears to have an external LNA chip and SAW filter so it's performance with the small 18mm antenna isn't as bad as I feared.

[RayRegan]

So........long story short, it's a POS. It would function if you configure it and then never turn off your aircraft, but that's not practical. Bummer!

Thanks for sharing.

[TheOtherCliff]

Quite OK if you want small on a Revo (which does all the auto-configuration at each power up), but not useful for CC3D.

What is the power on baud rate and protocol?

[hwh]

Mine powers up at 9600 sending NMEA sentences.