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Motor Channel C - Possible PCB CAM Error

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Blake Hament

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Jun 7, 2019, 3:59:10 PM6/7/19
to WoodenHaptics users and developers
Hello,

I've been debugging my motor channel C. I have good electrical connections and working quad differential line receivers across the motherboard. When I plug in a motor and driver chip in channel C, it is properly powered and I can read and write signals to the motor/encoder combo by connecting directly with USB and using the Maxon studio software. With these components tested, I think my issue must be with the daughter board or software.

When I was having the PCBs made, the PCB fabricator company responded with the attached PDF. There is a trace that is almost connected to a pad, but there is a small gap. To me, it looked like the trace should be connected, maybe the error came from a file conversion between eagle and gerber. I had the daughter board fabricated with the trace and pad connected, but maybe the trace should not be connected and that's why I am not getting signal from motor channel C?

From my interpretation of the schematics and board, I think the qaud differential line receivers are conditioning the raw motor/encoder signals, then passing to the motor driver chips and also to analog input of DAQ. So it looks like the trace is delivering an output from channel C to the DAQ analog input, and we do want it connected. Sounds about right?

Will continue on to DAQ and software debugging.

I appreciate your time and support with this project,
Blake
01987I_Error_BS5ca6794c2c273_daq_extention_board_20190404233820.pdf

Jonas Forsslund

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Jun 11, 2019, 1:55:15 AM6/11/19
to WoodenHaptics users and developers
Hi,
The pin that looks broken is the "enable" pin used by all three escons. When they are blinking they are not enabled, and no power would be provided to the motors. When they are enabled and running they should have a continous green light. From the DAQ the enable pin is "analogue" acting as a digital. Next to it you have the analogue set value signals for respective motor. 

However, if you have issues reading the encoder values it has nothing to do with this. Try with connecting the encoder cable to a different channel. The encoders are routed to the J4 connector as you see on top of your attached image. 

By the way, the differential decoding chips are not strictly needed, you can bypass them and using only the A- and B- signals (if I remember correctly).

Jonas

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