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How is the M3 wired to the Raspberry PI?
Posted: Mon May 04, 2020 11:02 am
by Mach
I see that the M3 has an integrated Raspberry PI for octoprint next to the Rambo board housing. It does not appear to be connected through the USB port. So how is it connected?
Re: How is the M3 wired to the Raspberry PI?
Posted: Tue May 05, 2020 5:52 am
by whoDat
It's connected via serial port connection ( /dev/ttyS0 ). You can see this in the Octoprint settings under the "Serial Connection" section. The rx/tx pins for this are on the GPIO header of the Raspberry Pi.
http://www.anintegratedworld.com/wp-con ... 08/pin.jpg
wh0dat
Re: How is the M3 wired to the Raspberry PI?
Posted: Tue May 05, 2020 3:53 pm
by Mach
Thanks for that. I spoke with support yesterday. There is apparently a daughter board in the mix that is not available as an upgrade. I'm assuming its a level converter to change from 5v to 3.3v for TX/RX pins. Not sure how the 5v power is being tapped to power the PI. It appears to be powered from the PSU. My plan is to use the GPIO header from a voltage regulator tapped to the PSU. It skips the polyfuse but should be ok downstream of the voltage regulator.
Edit: a follow-up on this one - got everything wired to test on separate power supplies. It worked intermittently on /dev/ttyAMA0. I'm guessing its noise and will re-try once the PSU is wired in. Otherwise, I'm going to punt on this idea and just get a short right angle USB cable.
