How to setup FDCAN on STM32MP157F-DK2?

[SScar.2]

Hi everyone!

I'm here with my devkit and trying to have FDCAN working properly! I compiled the Yocto distribution for the board and I followed all the tutorials in the wiki ( https://wiki.st.com/stm32mpu/wiki/Category:CAN ) and here's what I came up with:

I initialized m_can1

&m_can1 {

pinctrl-names = "default", "sleep";

pinctrl-0 = <&m_can1_pins_b>;

pinctrl-1 = <&m_can1_sleep_pins_b>;

status = "okay";

};

I used the pins_b configuration because looking at the datasheet they were the only possible exposed pins on the PI_GPIO extender (CN2) on the board (overwriting I2C5 pins for the Arduino). I also removed the pullup resistors for i2c (R166 and R167).

On the kernel side I tried the loopback and seems to work fine:

root@stm32mp1:~# ip link set can0 up type can bitrate 1000000 dbitrate 2000000 fd on

[ 1602.982564] m_can_platform 4400e000.can can0: bitrate error 0.3%

[ 1602.988958] m_can_platform 4400e000.can can0: bitrate error 0.3%

[ 1602.994593] IPv6: ADDRCONF(NETDEV_CHANGE): can0: link becomes ready

(the second bitrate error is different from the tutorials...) and seems working ok

root@stm32mp1:~# candump can0 -L &

root@stm32mp1:~# cansend can0 300#AC.AB.AD.AE.75.49.AD.D1

(1669130989.509567) can0 300#ACABADAE7549ADD1

(1669130989.509533) can0 300#ACABADAE7549ADD1

Now, I'm trying to get some data on the physical bus but it seems not working, I attached the oscilloscope on the pin PA12 (EXP_GPIO2) which should be the FDCAN tx, and enabled the bus as the example :

ip link set can0 up type can bitrate 1000000 dbitrate 2000000 fd on

But I can see absolutely nothing on the pin if I send any packet with cansend.

I also tried to attach a proper transceiver ( I used mikro CAN FD 3 click https://www.mikroe.com/can-fd-3-click --> TLE9251V based) , and after the cansend, the bus goes instantly bus-off :

root@stm32mp1:~# cansend can0 01a#11223344AABBCCFF

[ 706.810510] m_can_platform 4400e000.can can0: bus-off

Do you have any suggestions to make the protocol work properly? Do you have tried it yourself?

Huge thanks!

Simone

[GLaure]

For transceiver MCP2542 following pins have to be connected:

* 3.3V

* 5V

* GND

* TX to MC2542 RX

* RX to MC2542 TX

Note: Do not forget to cross TX/RX!

Function	STM32 pin	Pin		To MCP
3V3			-			1		3V3
5V			-			2		5V
GPIO2		PA12		3		RX
GPIO3		PA11		4		TX
GND		-			9		GND

This worked for me.

Bye Gunther

[SScar.2]

Hi @GLaure​ 

thanks for the answer! I din't attach both alimetations, I'll try that.

I have some questions: did you enable m_can only in the kernel dts just like me, or also in uboot? Also, did you removed the resistors as I did? Did you follow the same steps I did?

Thank you SO MUCH

simone

[GLaure]

Just in the kernel dts. It does not have to be configured by u-boot.

I did not remove any resistors.

[SScar.2]

Ok thanks... i'll try then

[ienecode]

@Javier1 

Hi, I am trying run CAN. But I have weird problem, which one described below:

can-communication-on-stm32mp157f-dk2 

Do you have any idea what can be wrong ?

 

[Javier1]

Never touched openlinux or any MP board, sorry

[ienecode]

@SScar.2maybe do you have any idea what can be wrong with my CAN communication described below ?

can-communication-on-stm32mp157f-dk2 

I noticed that we use different transceiver. You used CAN FD 3 Click , and I used MCP2542 Click .

@SScar.2  Do you think it might have something to do with my problem ?