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ASuar.1
ASuar.1
Associate III
Aug 7, 2020 5:12 PM UTC
Question

STM32MP1 FDCAN 1 or 2 not working

I am configured both the FDCAN interfaces on the STM32MP1 discovery board with the settings below using STM32CubeMX.

FDCAN1: PA11 (RX) PA12 (TX)

FDCAN2: PB12 (RX) PB13 (TX)

But I can't seem to get any data from either interface. I have a logic analyzer connected and have verified that there are packets going to the discovery board but candump doesn't show anything and cansend doesn't seem to be sending out any frames.

I also use the following command to turn on each interface.

ip link set can0 type can bitrate 500000

ifconfig can0 up

Am I missing something in the settings?

Thanks,

This topic has been closed for replies.

3 replies

ASuar.1
ASuar.1Author
Associate III
Aug 10, 2020 12:56 PM UTC

Looking further into the problem it seems to be caused by the FDCAN pins not being initialized.

When I put the can interface into loopback mode I am able to see the packets that I send. But when I do a physical loop back connecting RX to TX I don't see anything.

Is there a reason certain gpio would not be configured correctly at boot? And are there work around?

ASuar.1
ASuar.1Author
Associate III
Aug 10, 2020 3:52 PM UTC

So removing the "sleep" from the device tree of the both kernel and u-boot seemed to have fixed it.

&m_can2{
	pinctrl-names = "default", "sleep";
	pinctrl-0 = <&fdcan2_pins_mx>;
	pinctrl-1 = <&fdcan2_sleep_pins_mx>;
	status = "okay";
 
	/* USER CODE BEGIN m_can2 */
	can-transceiver {
		max-bitrate = <5000000>;
	};
	/* USER CODE END m_can2 */
};

mrnuke
mrnuke
Associate II
Jan 11, 2021 8:40 PM UTC

Hi @ASuar.1​ 

I'm sorry you're having issues with CAN. I am seeing the exact same issue. Your post saved me a lot of time, and my client a lot of money. Thank you! I wish somebody at ST would take a look and fix the underlying problem.

This is my workaround for CAN1:

 &m_can1 {
-	pinctrl-names = "default", "sleep";
+	pinctrl-names = "default";
 	pinctrl-0 = <&m_can1_pins_b> ;
-	pinctrl-1 = <&m_can1_sleep_pins_b>;
 	status = "okay";
 }

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