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nornagon / saxi

Tools & library for driving the AxiDraw pen plotter
GNU Affero General Public License v3.0
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Pi-Zero: OTG configuration #180

Closed osresearch closed 1 year ago

osresearch commented 1 year ago

Document how to setup the Pi Zero with a special "OTG" cable to power the Pi from the AxiDraw's servo regulator and connect the Pi's Micro USB to the AxiDraw's Micro USB.

jedahan commented 1 year ago

Did you modify the default cmdline.txt as well to include modules-load=dwc2 or is that unnecessary?

jedahan commented 1 year ago

I was able to replicate this (though my cable is a bit less pretty) - thanks for the info!

osresearch commented 1 year ago

@nornagon Any thoughts on merging this documentation fix for other Pi 0 users wire up their axidraws?

superhighfives commented 11 months ago

Would anyone be up for writing a brief overview of how to do this? Just trying to understand the relationship between the two usb cables and the headers, and how to splice that together.

For example, would something like this work, or would the fact that only one is powered be an issue? Would it require two data + power friendly micro-usb cables to be spliced together?

image

Actually, to simplify the question, I should probably just ask: what is happening in this bit of the image?

image
osresearch commented 11 months ago

I don't think that cable would work since there are no USB-A connectors available and the power-only connector doesn't have data lines.

My setup was made from two USB micro cables; If you have an old EBB with a Mini plug, then you can make a custom Mini-to-Micro cable. At the minimum you need to cut the micro ends off and strip the wires back. connect red to red, black to black, white to white, and green to green so that you have a straight-through double ended cable. If you also want to power the Pi from it, the red and black need addition wires with 0.1" headers on them to take +5V from the Axidraw's servo rail. The servo headers have three pins, black for ground, red for power, and white for data -- you only need to connect to the black and red.