Thanks for providing such a great forum for exchanging experience with arial drones. This has already proven a very helpful resource. I'm working on a Makani like kite energy project, but for now I'm just trying to get my Wing Wing Z84 out flying with Telemetry.
I'm currently in (Shenzhen, China) so of cause I got some 3DR V2 like Telemetry radio. My Radio works perfectly fine when I put them both in my laptop using the micro USB.
The main problem is that when I plug in my radio to the Pixracer, then it enters Bootloader more (solid red LED) 97% of the time. Appox. 1/30, it will connect with solid green and work transfer data nicely. I have attached a screenshot of the radio settings from AMP Planner 2.0. I currently have a 1.5.0 Dev version of the PX4 flight stack on the Pix Racer, but I have also tried with the official 1.4.4 available through qGroundControl.
Also a picture showing a test setup with red light on. If I just apply power it will also light up red (5V and ground connected).
Is this a fault with the radio, or is there some settings in the PX4 software that I can change to avoid this problem. I did see for ArduPilot (which i'm not using), that it's possible to put in a delay before telemetry data is being sent.
Any input would be appreciated. Would also liked to be a bit more informed, if I need to try to return it to the Chinese seller. Thanks! Hope you can help me get going so I can contribute the community later.
Thanks All for this investigation. Was very helpful.
Bought four same modules (500 mW). All with this issue. Fix work for them.
Trace can be cut without removing shield. Careful under the magnifying glass cut marked trace with small knife or scalpel. Don't cut too close to shield. Photo attached.
My modules have 4-pins connector. It is better to buy other modules with 6-pin connectors. On those modules CTS connected to one of pins in connector. Not to CP2102 chip.
Did more tests with these modules.
I found out that issues appear with my new Pixhawk 2.4.8, but work fine with my old 2.4.5.
Tests (more than 25 tests on each connection):
Almost always bootloader mode. No matter how powered.
Controller USB powered, module connected and powered from top connector - OK
Controller powered from servo rail (BEC), module connected and powered from top connector - OK
Controller powered from servo rail (BEC), module connected to top but powered from servo rail - BAD (Almost always bootloader mode)
I do not currently have a 3DR power module but i think result will be same as powering from BEC. Will have it and test in a few days later.
Also issues appear when powering radio from external source without tx/rx connection.
Pixhawk 2.4.8 is a cheaper and simplified version of 2.4.6. From 2.4.8 manufacturers removed many important components. Power system simplified and similar to pixracer. Also level registers on I/O replaced with simple resistors. I looked at Pixracer schematic and it have same changes.
I think that this is the case.
Interesting fact: 500 mW radio module consume from 150 to 450 mA when transfering data. Measured when testing. It is a lot. I look on schematic and found 350 mA fuse in I/O circuit (2.4.6 version of px). I think module must be modified and powered from external BEC even if using on 2.4.6 (or similar).