CAN1 loopback does not work on STM32F427

[Louis00]

Hello everyone,

I have recently been trying to get the CAN1 bus working on the STM32F427. So far, however, it has not worked in either loopback or normal mode. For the normal mode I had a CANCaseXL Analyzer available. The problem, however, is that not even the loopback works. I have attached the main.c file and the ioc project file.

When I call HAL_CAN_AddTxMessage(), I get HAL_OK back, so that seems to work. However, I have set a breakpoint in the CAN interrupt handler (HAL_CAN_IRQHandler() in file stm32f4xx_hal_can.c) and there I see that the TERR0 bit gets set. Accordingly, the transmission process has failed. I have already tried many other possibilities, which unfortunately did not work either.

Maybe someone has an idea. Many thanks in advance!

Louis

[SofLit]

Hello,

At first check at your ioc file, I don't recommend these values for CAN bit timing:

hcan1.Init.Prescaler = 16;
hcan1.Init.TimeSeg1 = CAN_BS1_1TQ;
hcan1.Init.TimeSeg2 = CAN_BS2_2TQ;

BS1_1TQ and BS2_2TQ are very low. You need to increase them as much as possible by decreasing the prescaler as much as possible.

I recommend these values for 500kb/s:

Also, we don't recommend HSI as clock source when using CAN in Normal mode. You need to use HSE with an external crystal otherwise you may face communication issues.