Hi DIY.
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.
/Andreas
Replies
Thank you.
Now it is working.
Viсtor Klimov said:
Try to disconnect the CTS and RTS wires. Use needle and remove them from connector.
Pavel Srnsky said:
Hello,
i would like to ask for the support even if the topic is little bit old. I have exactly the same problem described in discussion. With the telemetry radio (probably the clone of 3DR 433mhz) connected in my case to the pixhawk 2 (cube) it's working when usb powered from laptop but solid red led when powered by battery through FC.
Could you please help me, if I can cut some trace or cable to get it work?
Thank you
81608878_565917790896877_2107271247892054016_n.jpg
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):
Pixhawk 2.4.8:
Almost always bootloader mode. No matter how powered.
Pixhawk 2.4.5:
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).
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.
Thanks All,
I had the the same issue and used this procedure. Its all working now. Unfortunately Banggood was no help.
Dmitry Ovcharov said:
Thanks for providing the photo of the fix, I just bought a pair of these 915mhz with the same problem described above. I made the fix, they did a real good job of soldering to the CTS pad. I will be doing the other one to also use it as an air radio, I have the radios that came with my APM 2.8 and will continue using the ground radio that came with it. For the radios I have it was a matter of making sure the solder joint between the pad and the radio CTS pad was also cut.
Thanks for including the photo. If you can send the photo to Andy Vo at Thanksbuyer (thanksbuyer@aol.com) he will attempt to negotiate a fix with the manufacturer. These radios have been shipped all over the world in 433 and 915 MHz variants, and none of them work (as air radios) without this time consuming repair. Most go straight in the trash.
Ronald, thank you very much. Your solution worked. We identified CTS pad on the PCB of the radio module, and cut the trace to it. Now the radio module starts fine when I plug in the battery to the quadcopter.
For those "lucky" guys who end up with the same radio modules, here's the photo of the trace you need to cut. It's the trace which comes to the third contact pad from the right. when you look at opened module under the metal cap.
Hi Dmitry. If you study the telemetry radio you will find it is designed such that "you can force bootloader mode by shorting the CTS and GROUND pins on the radio while powering on." The problem with this radio is that CTS is connected to the UART such that the voltage on CTS is pulled down during startup. You can "fix" the radio by cutting the trace between CTS and UART. Unfortunately I did not take a photo before gluing the radio back in the case, but you can find schematics and photos online, and it is easy to follow the trace for the CTS to the UART. I went through the process of evaluating the problem and executing a repair for fun. Otherwise it is not worth the effort. My suggestion is you dedicate the radios as "ground radios" and use other radios for "air radios."
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