[imazman]

I don't know a lot about quads, hardware, and software.  However, I currently have a QAV250 fpv racer that i built about a year ago.  I want to build a new QAV250 primarily for autonomous flight and as a FPV as a secondary purpose.  My racer uses CC3D so I am somewhat familiar with LibrePilot.  The guys I work with have 2000 to 4000 name brand drones which have amazing autonomous capabilites...but they fly very slow and I am a speed junky.   I will be building a new quad for autonomous flight (I know I won't get close the the easy usability and features they have) and have been researching for hardware for a long time and have just come across Sparky 2 information.  Sparky 2 has really clear instructions and I like the TauLink which has USB right on it. 
A guy at work gave me a GPS (Ublox M7) and a handheld FS-TH9X controller (says 3DR when I turn it on) but controller doesn't have the transmitter module that plugs into the back nor a receiver for the quad...but it has PPM capability.  I don't think the handheld controller has a transmitter built in either, because where the antenna would come out of the controller it is just a hole with a plug in the top.  My racer uses a Walker Devo7 and doesn't have PPM capability nor a changable module on the back so I would like to move forward with using the FS-TH9X on my new quad.  I found the transmitter module and a receiver online both for about $50...but I'm not sure I need the either of these parts (see questions below).   I already bought motors, ESC, frame, fpv camera, and video transmitter.

Now for my FC...what are the pros and cons between Sparky2 and Revolution? 

They both have 433MHz which is another requirement of mine and they both can work with LibrePilot.  With all the different hardware, software, old web sites, etc...it all seems so overwhelming and I also have other questions that I need to continue to research but if any one can answer these I would be greatly appreciative.
  - Will any transmitter module work in a FS-TH9X? 
  - Does the OpLink connect into the back of a handheld controller like the FS-TH9X or is the OpLink meant to be plugged into a computer?
  - Does the TauLink connect into the back of a handheld controller like the FS-TH9X or is the TauLink meant to be plugged into a computer?
  - If I use the OpLink or TauLink...do I still nee to have a receiver on my quad...like a RX701 (walkera compatible receiver)...or does the Revo's and Sparky2's receiver take the place of the typical receiver that is typically supplied with the purchase of a new handheld controller like the Walkera Devo 7 and FS-TH9X?
  - Should I research the Pixhawk FC?  (I don't really want to add more confusion into a sea of overwhelming information)

Again any and all help and comments are greatly appreciated!
/Z/

[Mateusz]

Revo and Sparky2 have the same bed module for 433. So you can use oplink with Sparky2. The only difference between Revo and Sparky2 is newer sensor and Sparky2 lacks flexibleIO port but has i2c port and 3 pin receiver port. Everything else is the same. Sparky2 is newer design.

Oplink can do both telemetry and ppm. It can be plugged to computer, you can connect Bluetooth module to it and use your Android device with it. Taranis has ppm input under transmitter bay so you can connect oplink ppm output there and set up Taranis to use it.
Taulink is just modified oplink.

About GPS I suggest using DJI Naza one as it uses just one cable to send both GPS and Mag data.

On 250mm build you do really need to keep Magnetometer away from the rest of copter and motors. You need mast 11-14cm that carries GPS+mag combo. Another thing is you must make sure your fpv 5G video transmiter is not interfering with GPS which may lead to lost satellite and spikes. You could also consider helical antenna instead of patch to reduce multipath reflections GPS may be confused with.

Pixhawk is just heavier and not necessarily better (depends on personal opinion).

I would use Revo or Sparky2, if you have Revo then you don't need another FC. If you want to buy one, go with Sparky2.

Also when you get FC check barometer in scopes that it is varing when copter moved and does not exceeded +-0.5m error in altitude when stationary.

[imazman]

Thanks for the information Mateusz!  I think I will go with Sparky2 and TauLink.  So if I understand you correctly i won't need to purchase the original transmitter module for the hand-held controller and I won't have to purchase the original aircraft receiver that went with the handheld controller.  If true, then I will be able to save $50+ that I was expecting to have to shell out!

As far as the GPS...coworker gave me a brand new IBlox 7M...it does have two cords, one for GPS and one for compass...does that mean I can't use it with Sparky2 or just that it will use up an extra interface.  What are some examples of what the used up interface would/could be used for?   I will ask a few more coworkers to see if they have any DJI Naza's they aren't using.

Pixhawk...guy at work was going to give me one...but it was much bigger too...so I passed on it (plus I was afraid I would have to learn all new ground control station software).

And thanks for the tips about the GPS interference and the barometer test!  I might try putting heating duct tape (metal tape) on the underside of the GPS radon and see if it help or hinders.  I also have an SDR which I can use to see if there is interference at the GPS band coming from video, motors, PDB, etc. 

[TheOtherCliff]

Taulinks are hard to find.  Use an OpLink.  They are basically the same.  OpLink also has USB on it.

[Mateusz]

Thanks for the information Mateusz!  I think I will go with Sparky2 and TauLink.  So if I understand you correctly i won't need to purchase the original transmitter module for the hand-held controller and I won't have to purchase the original aircraft receiver that went with the handheld controller.  If true, then I will be able to save $50+ that I was expecting to have to shell out!

• TauLink is not commercially available to my knowledge (you can only build one yourself). There are only OPLinks to buy from cloners. TauLink is a derivative of OPlink. Both use the same NRF radio chip and are compatible.
• Sparky2 has "oplink" module and can talk with OPlink usb dongle.
• Yes you can use OPlink as transmitter to control air-craft. There are 3d-printed cases to mount OPlink on the back of Taranis http://www.thingiverse.com/thing:702865

As far as the GPS...coworker gave me a brand new IBlox 7M...it does have two cords, one for GPS and one for compass...does that mean I can't use it with Sparky2 or just that it will use up an extra interface.  What are some examples of what the used up interface would/could be used for?   I will ask a few more coworkers to see if they have any DJI Naza's they aren't using.

It probably means that your GPS does not have built-in Compas (magnetometer) or wires are just not connected. Open GPS case and check if there is a chip L883 symbol (see attached picture for external magnetometer board). The L883 chip is the actual magnetometer. It must be mounted far from other electronics and aligned with built-in in FC magnetometer, so they both show the same thing. This is I2C connection (+,0,sda,scl) 4 wires. GPS with L833 has two extra wires for SDA (data) and SCL (clock). But I2C is short distance bus, and you need to mount magnetometer far away. This is conflicting and sometimes problematic to get good signal. Best is to get GPS that has built-in magnetometer but talks protocol that incorporates Mag measurements inside GPS messages. LibrePilot supports DJI GPS which does this. Then you dont have any problems with I2C connection. But if you really want you can try I2C.

Pixhawk...guy at work was going to give me one...but it was much bigger too...so I passed on it (plus I was afraid I would have to learn all new ground control station software).

Pixhawk is ok hardware, except it's big and heavy, I dont like their software as well.

And thanks for the tips about the GPS interference and the barometer test!  I might try putting heating duct tape (metal tape) on the underside of the GPS radon and see if it help or hinders.  I also have an SDR which I can use to see if there is interference at the GPS band coming from video, motors, PDB, etc.

Remember to use case to protect baro from light (it is light sensitive)
Remember to use sponge that let air through but protects baro from wind blows.

Finally about Sparky2 vs Revo. Sparky2 has newer MPU9250 sensor, but it's gyro has a bit higher noise levels then older MPU6000 on Revo. Though this is not noticeable difference and you shouldn't bother about that.

[TheOtherCliff]

As far as the GPS...coworker gave me a brand new IBlox 7M...it does have two cords, one for GPS and one for compass...does that mean I can't use it with Sparky2 or just that it will use up an extra interface.

This should and usually means that GPS is on one (serial) interface and mag is on a second (I2C) interface.  I2C must be on Flexiport for Revo or Nano.  I2C must be on Flexiport or I2CPort for Sparky2.  Sometimes though, a cheap manufacturer does not include the mag chip when populating the board.