STM32H725 FDCAN：A CAN bus fault is caused when the FDCAN is Stoped

[guo qiang]

One VCU controller A, one USBCAN converter B, one my H7 device C.

A is sending, B and C are receiving. When C Stop FDCAN, both A and B report a bus failure.

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One VCU controller A, two USBCAN converters B1 and B2, . A is transmitting, B1 and B2 are receiving. When B1 stops FDCAN, A and B2 are fine and do not report bus errors

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USBCAN converters(B，B1,B2) are known to be a standard product and have passed the certification of many testing bodies.

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So I think my H7 device caused a bus failure when it stopped FDCAN.

my code:

HAL_FDCAN_Stop(&hcan1);

​Transceiver:MCP25612FD

CANFD configuration:

Classic CAN, 500K

[LCE]

Sorry I cannot help... but I'm curious:

what happens if you do not call HAL_FDCAN_Stop(), but:

• remove the CAN cable from the H7
• power down the H7 board

?

And do the other devices recover from bus errors?

[guo qiang]

• remove the CAN cable from the H7
• power down the H7 board

-->other device not report can bus errors.

[LCE]

Okay, that's bad.

Then the HAL CAN driver is doing something which it should not do.

Maybe check the RM again what's happening when HAL_FDCAN_Stop() is called, bit by bit.

[LCE]

Although it would be a kind of workaround, maybe before calling HAL_FDCAN_Stop() you could reset the CAN GPIOs to take it off the bus.

Before that check the idle state of the CAN TX pin and set the GPIO accordingly, unless there's a pull resistor.