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Using st link v3 to program over CAN


Good day,

I am attempting to program an STM32L5 MCU using an ST Link V3 over FDCAN. I am aware that on the breakout board for the ST Link V3 there is connector CN5 which has CAN RX and TX. On the microcontroller I have a CAN transceiver installed on pins PD0 and PD1. I am able to put the microcontroller in the bootloader mode, but when I attempt to connect using the following configuration


all I am met with is the error
22:56:39 : Error: ST-LINK error (BRG_CAN_ERR)
22:56:39 : Error: Establishing connection with the device failed

Do I have to use pins PB9 and PB8? If so, do they have to have a CAN transceiver installed on them? Am I doing something wrong in CubeProgrammer? Should I be using a different connector on the ST Link V3? Programming over UART was so easy I did not expect CAN to be anywhere near this difficult. Any assistance would be greatly appreciated as this is somewhat urgent. Thank you.





My expection is that you need a transceiver on the ST-LINK/V3 side also. Or use the diode method at both ends in lieu of the transceivers. 

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Have you gotten this working with pins other than the ones specifically mentioned in the bootloader documentation?


ST Employee

Hello @Eben,

Please check the steps in this article. If you still encounter any issues afterwards, feel free to reach out.



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