CAN BUS Throttle issue

[Bigpie]

I'm having an erratic throttle at the inverter, the min throttle value is 815.

My setup is a rev 3 main board running stm32-car and a Prius gen 3 inverter board from EVBMW

The signal is steady on the rev 3 board and the CAN BUS logs are outputting a steady 815/816 but the inverter keeps dropping.

Can H to L resistance is 45 ohms, so no the ideal 60, not sure if this could be the cause?

Throttle signal is ID: 0x01 starting at bit 0 and is 12 bits long.

Any suggestions to what could be the cause would be great. TIA

Savvycan filtered log attached.

Code: Select all

Timestamp	pot (avg)	pot (min)	pot (max)
2021-05-01T17:29:45.914	307.98	46	815
2021-05-01T17:29:46.346	318.98	46	816
2021-05-01T17:29:46.901	363.89	47	816
2021-05-01T17:29:47.374	305.3	47	816
2021-05-01T17:29:47.949	303.61	47	815
2021-05-01T17:29:48.781	298.61	46	815
2021-05-01T17:29:49.393	303.68	47	816
2021-05-01T17:29:50.461	308.04	46	815
2021-05-01T17:29:51.127	334.3	47	815
2021-05-01T17:29:51.606	300.23	46	816
2021-05-01T17:29:51.960	338.68	46	816
2021-05-01T17:29:52.283	299.05	47	815
2021-05-01T17:29:52.611	323.53	46	816
2021-05-01T17:29:52.957	354.43	47	816
2021-05-01T17:29:53.284	344.81	46	815
2021-05-01T17:29:53.634	312.58	46	815
2021-05-01T17:29:54.107	346.37	46	816
2021-05-01T17:29:54.624	349.36	46	816
2021-05-01T17:29:55.136	303.73	46	816
2021-05-01T17:29:55.607	356.05	47	816
2021-05-01T17:29:55.932	317.24	44	816
2021-05-01T17:29:56.320	334.45	47	816
2021-05-01T17:29:56.659	301.98	47	815
2021-05-01T17:29:56.999	322.05	46	816
2021-05-01T17:29:57.323	309.82	47	816
2021-05-01T17:29:57.662	340.33	46	815
2021-05-01T17:29:58.001	308.15	46	816
2021-05-01T17:29:58.334	303.31	46	816
2021-05-01T17:29:58.749	320.62	47	815
2021-05-01T17:29:59.350	326.74	46	816
2021-05-01T17:29:59.801	317.21	46	816
2021-05-01T17:30:00.161	331.14	46	816
2021-05-01T17:30:00.525	326.47	47	815
2021-05-01T17:30:00.871	340.23	46	815
2021-05-01T17:30:01.221	329.74	47	816
2021-05-01T17:30:01.757	318.04	47	816
2021-05-01T17:30:02.348	305.3	47	816
2021-05-01T17:30:02.927	345.07	47	816
2021-05-01T17:30:04.067	357.22	46	816
2021-05-01T17:30:04.715	303.76	46	816
2021-05-01T17:30:05.037	326.41	46	815
2021-05-01T17:30:05.370	308.09	46	816
2021-05-01T17:30:05.750	303.6	47	816
2021-05-01T17:30:06.223	331.33	47	816
2021-05-01T17:30:06.708	305.22	46	816
2021-05-01T17:30:07.343	343.39	46	816
2021-05-01T17:30:07.934	365.11	47	816
2021-05-01T17:30:08.266	325.02	47	815
2021-05-01T17:30:08.645	329.82	47	816
2021-05-01T17:30:08.979	311.53	47	816
2021-05-01T17:30:09.427	345.2	47	816
2021-05-01T17:30:09.759	305.63	47	816
2021-05-01T17:30:10.085	347.91	46	815
2021-05-01T17:30:10.460	323.62	47	815
2021-05-01T17:30:10.800	305.22	47	816
2021-05-01T17:30:11.146	307.15	47	816
2021-05-01T17:30:11.486	340.46	47	816
2021-05-01T17:30:12.044	361.74	46	815
2021-05-01T17:30:12.589	317.22	46	816
2021-05-01T17:30:13.211	306.67	47	816
2021-05-01T17:30:13.606	313.29	47	816
2021-05-01T17:30:13.957	331.36	47	816
2021-05-01T17:30:14.525	346.88	47	816
2021-05-01T17:30:15.040	319.06	46	816
2021-05-01T17:30:17.178	311.19	47	815

[johu]

Hmm, CAN bus seems terminated at three locations (120/3 = 40 Ohms). Would think it's a physical CAN bus issue.

EDIT: Also check stm32_can.cpp the call to can_init()

Code: Select all

	can_init(canDev,
		     false,          // TTCM: Time triggered comm mode?
		     true,           // ABOM: Automatic bus-off management?
		     false,          // AWUM: Automatic wakeup mode?
		     false,          // NART: No automatic retransmission?
		     false,          // RFLM: Receive FIFO locked mode?
		     false,          // TXFP: Transmit FIFO priority?
		     CAN_BTR_SJW_1TQ,
		     canSpeed[baudrate].ts1,
		     canSpeed[baudrate].ts2,
		     canSpeed[baudrate].prescaler,				// BRP+1: Baud rate prescaler
		     false,
		     false);

5th argument (NART) must be set to false

Another edit: have you set potmode=CAN on the inverter? Looks like it's toggling between the CAN received values and the ADC measured one.

[Bigpie]

Genius, pot mode was singleregen, spent hours on this assuming it was something complicated.

Can Bus is strange in my VW in that the ECU that I've ripped out had 66ohm resistor between H&L, the ABS node apparently has 2.6k between them and so too does the instrument cluster. I may need to change the resistors I've put in to replace the 66 to bring it closer to 60 ohm.

Hopefully get the car rolling tomorrow now though. Thanks

[johu]

Great! We've also learned that sensible logs are very helpful

Interesting bus layout, maybe no need to be so concerned about correct 120 Ohm termination only at the ends?

[EV_Builder]

Great! We've also learned that sensible logs are very helpful

Interesting bus layout, maybe no need to be so concerned about correct 120 Ohm termination only at the ends?

Yeah canbus is quite forgiven these days or manufacturers have something in place that dynamicly terminates the bus. So if a device is disconnected the bus is still active.