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collin80 / GEVCU6

Generalized Vehicle Control Unit for version 6 boards
MIT License
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CAN Bus not working #4

Closed bsculley closed 5 years ago

bsculley commented 6 years ago

I am having problems getting the GEVCU CAN bus to work. I am using CAN0, with A2 as CANH0 and B2 as CANL0 on the 30 pin connector. I have the PowerKey keyboard and a CAN monitoring board on the CAN network (both at 500000 baud). I can see the CAN messages from the PowerKey, so I think the bus is functioning ok.

I put a log trace in at CanHandler::process, with the following results:

9246 - INFO: CAN: status=2162880 speed=500000 9247 - INFO: CAN: status=1151729664 speed=500000 9248 - INFO: CAN: status=2162880 speed=500000 9250 - INFO: CAN: status=1151729664 speed=500000

I have no way to interpret the status values.

I have tried simple hardware debugging:

Resistance (unpowered) between CANH0->GND and CANL0->GND seems to be infinite (no reading) in both cases.

The voltage (powered, obviously) between CANH0->GND and CANL0->GND is 0 in both cases. All measurements are at the wires from the 30 pin connector. I have verified that the multi-meter is working. Other devices show nominal readings.

Don't know what I'm doing wrong. Any ideas gratefully accepted.

bsculley commented 6 years ago

Further to this issue, I have tried using CAN1 with the same results.

collin80 commented 6 years ago

With the CANH0 and CANL0 wires not connected to anything else what is the resistance between them? It should be 120 ohms. They're isolated floating differential wires you won't necessarily get good readings to ground. You can basically only read between them. It's been too long since I saw where those status flags even come from. I'll try to look that up.

bsculley commented 6 years ago

Thanks for the tip. I get 120 ohms between the H/L lines when measured at the terminals on the GEVCU, however, I get nothing when measured at the ends of the wires on the cinch plug. I have verified that it is seated as far as possible and, in fact, some other terminals are connected, e.g. A0.

I have gotten the CAN working by connecting some jumper wires directly to the terminals on the GEVCO. I believe there is some defect in the cinch plug wiring or mechanics.

Bob

From: Collin Kidder notifications@github.com Sent: Friday, September 7, 2018 4:27 PM To: collin80/GEVCU6 GEVCU6@noreply.github.com Cc: bsculley bsculley@IntegratedSoftwareSvcs.com; Author author@noreply.github.com Subject: Re: [collin80/GEVCU6] CAN Bus not working (#4)

With the CANH0 and CANL0 wires not connected to anything else what is the resistance between them? It should be 120 ohms. They're isolated floating differential wires you won't necessarily get good readings to ground. You can basically only read between them. It's been too long since I saw where those status flags even come from. I'll try to look that up.

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