Probably related to the Failsafe problem, but i have an issue with 2 different copters running micro Vrbrain 5.1 and D4R-II 27ms receivers(3.2 rc2) connected with ppm. Both of them go in failsafe after a while. No Rssi problems on my tarranis. In the mission planner failsafe screen i can see the signal dropping sometimes and coming up again after a few seconds. Since these are to separate machines i am at a guess what would be the reason. Needless to say this is serious issue for me. Any ideas?
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Hello,
I copied the link wrong video sorry.
Video
Well, my FC and RX combination would have surely gone into failsafe in that timeframe. We may need some more testing to be sure and incorporate the fix in a next revision of the Mvrbrain.
Hi Micha,
Today I tried the change I made and it worked out very well OK (Video). The modification consists of placing a resistor in series to 10-15Khom PPM signal, this decreases the voltage and the current flowing without saturating the input.
Usually the outputs of the receivers or PPM decoder, are 4.5 / 5Volt and strangely the entrance of Vbrain is 3Volt, it should be 0Volt is an input, I think it was programmed in mode INPUT_PULLUP.
I also tried a circuit Bi-Directional MOSFET Voltage Level Converter 3.3V to 5V but it did not work.
Tomorrow I will test higher to see if the change is safe, and that you do not repeat the fail-safe.
I hope that this change is also useful to you.
I believe that the inputs directly connected to the cpu and not filtered through the resistors in series with the protection and long connections can create some mismatches.
Emile You could do a test and put the input pin pullup not high, but low by software, it is only a test.
greetings
Fabio
There is a problem with the video but it sure looks you are on the right track. ;)
As you mention you want to use pwm i assume you are not using a FRsky D4R-II. What receiver are you using if i may ask?
I have to go do some aerial video work now. I will be back in the evening.
Hello Micha,
I've finished doing tests on VRµBRAIN, I focused on the levels of tension between the receiver and the VRµBRAIN.
I think I've solved the problem, the first once armed drone went after a few seconds in fail-safe, after the change, the drone once armed remained more than 25 minutes without having a failsafe. Tomorrow I make the latest evidence and then I'll give you the news, I hope positive and definitive about changing that I did, for my problem that similar if not the same as yours.
For the PWM using a receiver Turnigy 9X8C.
Greetings and good night
Fabio
Hello Micha,
I think it's a software problem, I visualized oscilloscope with the input signal to the processor pin the signal arrives clean and not distorted. My problem now is that I would like to load the firmware in PWM, but I can not for the error that gives me the mission planner in the upload of custom firmware.
Sob! Sob! :(
greetings
I am not sure if it is a software issue. But it is good news that the signal is clean at the board level. In that case 2 of my cables are still bogus as they fail to pass 5 volts. I have spend a day in corporation with Roberto to find a solution. We have tried several different versions of software, . But the fact that pixhawk works fine is strange. I used MP 1.3.7 24027 to upload custom firmwares Roberto give me without any problem. I presume you have read this? https://github.com/PX4/Firmware/issues/921
Hello Roberto,
As for the fail-safe radio the drone is armed and ready to take off with the GPS 19 satellite, so many that are taken off time to pull the cart from the ground that the drone went into failsafe radio and landed with my amazement did not understand what was happening.
Enters fail-safe mode randomly and not given in time, loses synchronism ppm although the timing that I measured is stable at 18ms.
It would be helpful if the beeper emits rhythmic beeping when you get into fail-safe mode to get a quick understanding of what is happening.
greetings
PPM is not fixed and has never been fixed. Of all my flight controllers the mVRbrain is the only one who has problems with it. After many hours trying to find the reasons i eventually gave up on it and was forced to buy Sbus recievers. A pricy solution. They just work fine. The issue is hardware related. Now i suspect my red 10 cable connections. By now i have 2 of them with bad connections. They fail to pass 5 volt to the reciever. I emailed 10 days ago to request where i can buy some but have yet to receive an answer.
Do not use PPM now and be very careful not to engage RTL in mission planner. A gps glitch while it randomly goes into failsafe would be catastofical and could lead to a fly away as you do not have the ability to use your switches to get out of it.
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