Hello, i have another problem with my APM. I suspect i have a fried MUX, here are my symptoms :
Do you think my APM board is fried ? do i need to change the red board only ? Is there other things to test to have a more precise diagnostic ? is it possible to revive the MUX ?
nobody has a clue for me ? :/ thanks,
If the MUX has been fried, it would need to be replaced, but since the MUX and PPM lights are on, it sounds like the board may not be fried. Did you say that you've reloaded the same arduplane firmware that you had been using before the problem with the channels, and that the problem has persisted? You can try reflashing the 328 chip and see if this helps: here are instructions for how to reflash the chip here in the ArduPlane manual. Hope this helps!
I have the same problem. The one lighting is the Power, and MUX (in red) but the PPM Lights does not light up? What do you think is the problem. It also doesn't receive input from the radio. Is it fried? Is it the MUX? If it is, is it possible to replace it? This thing happened to us twice already.
To make sure I understood: on the red APM board, do you only see the red LED light up when the board is powered? Or do both the red power light and yellow MUX light turn on? If only the red light turns on, then it sounds like a hardware failure and the MUX and 328 chip, or the entire board may need to be replaced, and you may want to contact tech support at the store from which you purchased the board.
To replace the MUX chip, you can simply remove it and replace it with a new MUX chip.
If I may ask, what could have caused this problem?
small update : i'm waiting for the programmer to arrive to reprogram the chip...
Marianne> what happened to the boards since ? have they magically worked again ?
it didnt. We tried uploading code via ftdi. unfortunately, this time no lights were on. But the arduino says that it's uploaded. would that be possible?
before this problem, the sensors were really crazy (literally sends wrong APM Movement shown in the AP Mission Planner) or sometimes the data reading is so slow. We always reset the APM and voila, it works again. But just a minute ago, we were about to test the APM, the light sequence was already there. Red or Orange for MUX, Red Power and no PPM,
It's kind of hard to damage the MUX chip, the atmegas are pretty hardened, unless you've applied > 5v to it, and you shouldn't be able to do that with the power coming from the radio. I've shorted my input many times before by plugging in the jst plugs upside down.
You mentioned that you were running arduplane and now switched to arducopter, did you remember to reset the eeprom? The old settings may be making arducopter go nuts.
Also unplug all the radio input and only plug it in one channel at a time to figure out which channel on the APM may be bad.
interesting comment : you said : ", unless you've applied > 5v to it," may i interpret this as : "plugging a servo connector with power from it the wrong way round won't damage the mux" ? :)
Right, I'm speaking from experience, but I don't recommend doing this on purpose. I mean the input signal at the APM and decoder is ttl level (5v), and you can apply high or low, so as long as you kept the voltage 5v or below there's no way that the signal lines on the decoder, which is an atmega, can be damaged. You could blow the fuse on the arduino from crossing power lines, but since the APM is still running, this has not occurred. You could also damage your battery from shorting it, but that doesn't affect your APM.
Did you try resetting the EEPROM like I suggested, since you migrated from Arduplane to Arducopter?
Hi guys well apparently our board (marianne is my groupmate) seems to have a fried mux. I salvaged a working 328p from our 1280 board and the now the ppm led lights up already and I can see the pwm getting in already through the CLI. But unfortunately there's no output; I mean the servos doesn't move at all, I tried connecting the servos directly to the rx to see if its ok and yeah, it is ok so that left me with the idea that the mux is indeed fried.
Can I just buy the mux chip(74LS157D) and replace it directly? I mean does it need to be programmed like the atmega328p?
and oh, the apm doesn't power up when powered through the rc rail. So I tried powering it externally and unsoldering SJ1. Yes the apm powers up, but it can't read the pwm signals from the rx. Funny thing is, when i tried putting a jumper unto Vin( external voltage input to apm;beside SJ1) from the rc rail, viola, it powers up AND reads the pwm signals from the rx.
Hmm guys any ideas why this is happening? busted diode between the rc rail and internal vreg perhaps?
**errata** the mux chip not 74ls157D, but a 74ACT157