MobiFlight Community Support

Hi,

I am using Mobiflight 9.0 for only 2 stepper gauges... altimeter and compass. While trying to calibrate the compass, Mobiflight has lost the configuration completely a handful of times, It would detect an arduino on next power up and ask if to upload firmware (which would work again), but twice would not even be able to re-upload firmware until I had to re-flash the bootloader with an external ISP programmer. This has happened with both a clone and a real Arduino, and with 2 different computers. Any idea what is causing this, and how to fix it?

Thanks.

Hi Neil,

welcome to MobiFlight!

How did you power you two stepper? With an external power unit or via the mega modul?
A stepper uses nearly 200mA quiescent current. With two you have ca. 400mA. When the steppers are turning the current raises up and if they need more than 500mA while mega powered, the voltage drops and the mega is not able to work well.
If you power them external, look that you have connected the GND of the external power unit with the GND of the mega.
if you have a multimeter check the voltage with it when the steppers are operating.
When uploading the firmware disconnect the steppers.
If you use these cheap USB cables (blue) which are deliverd with the mega, change them you have bought yourself or use the ones which have worked with other devices.
If you use an USB hub, check that it is switched on and delivers the needed 5V.
You see there are multiple causes why something not work as excepted.

Hi Stephan,

Thanks for the reply. This is what I have...

- Stepper driver logic (currently) powered from the Mega (there is external 5V for after is done being setup). Motor power is external 12V.
PC wiring: http://orlandorobotbuilders.com/stuff/Mobiflight-Wiring-01-PC.jpg
Laptop wiring: http://orlandorobotbuilders.com/stuff/Mobiflight-Wiring-02-Laptop.jpg
- Grounds are not connected together... for other stepper drivers I've used previously (CNC machines) motor & logic grounds had to be purposely isolated, as spikes on the motor side could cause issues with the logic side. Here, I am using smaller (TMC2208) drivers, so wasn't sure if they should be connected. I can try that.
- FWIW, power supplies are very capable... IIRC like 4A-5A, and not running much else.
- Using different USB cables... tried a couple different ones.
- I was using a hub with the PC at first, but took that out.

I'll try connecting the ground and see what happens.
When uploading firmware... do you mean disconnect the steppers, or disconnect the stepper power? Asking because the stepper connections are not easy to disconnect as it's setup currently.

Thanks.

I don't have access to the sim during the week, but someone else is testing this ground connection.
I'll report back.

Hi Stephan,

So we used a brand new Mega (this is #3) and connected the 12V ground to the 5V ground. Did not even get a chance to measure the voltage while operating, but both voltages are very good otherwise.
Same thing happened again, and the mega is locked up again where we would need to get the bootloader re-installed.

I'm stumped.