CAN over SPI

BaNe — Wed, 18 Jul 2018 09:47:53 GMT

I am using im8mq-evk board to test out a SPI to CAN converter. Namely the MCP2515 chip. I connected to ECSPI1 Signals with disconnecting the stuff on the evk board.

I removed all other uses of the pins from DTS file and added the pin configuration to iomuxc

        pinctrl_ecspi1: ecspi1grp {
           fsl,pins = <
               MX8MQ_IOMUXC_ECSPI1_MOSI_ECSPI1_MOSI       0x10b0
               MX8MQ_IOMUXC_ECSPI1_MISO_ECSPI1_MISO       0x10b0
               MX8MQ_IOMUXC_ECSPI1_SCLK_ECSPI1_SCLK       0x10b0
           >;
       };
       pinctrl_ecspi1_cs: ecspi1grp_cs {
           fsl,pins = <
               MX8MQ_IOMUXC_ECSPI1_SS0_ECSPI1_SS0       0x10b0
           >;
       };
       pinctrl_ecspi1irq: ecspi1irqgrp {
           fsl,pins = <
               MX8MQ_IOMUXC_UART3_TXD_GPIO5_IO27       0x4000056
           >;
       };

I also added DTS node for the clock of the chip and for ECSPI1

/ {
...
        clocks {
       can0_osc: clock@7 {
           compatible = "fixed-clock";
           #clock-cells = <0>;
           clock-frequency = <8000000>;
       };
   };
}
&ecspi1 {
    fsl,spi-num-chipselects = <1>;
   cs-gpios = <&gpio5 9 GPIO_ACTIVE_LOW>;
   pinctrl-names = "default";
   pinctrl-0 = <&pinctrl_ecspi1 &pinctrl_ecspi1_cs>;
   status = "okay";
    can0: mcp2515@0 {
       #address-cells = <1>;
       #size-cells = <0>;
            reg = <0>;
            compatible = "microchip,mcp2515";
       spi-max-frequency = <10000000>;
            clocks = <&can0_osc>;
            pinctrl-names = "default";
            pinctrl-0 = <&pinctrl_ecspi1irq>;
            interrupt-parent = <&gpio5>;
            interrupts = <27 IRQ_TYPE_EDGE_FALLING>;
   };
};

For the kernel I added builtin support for mcp251x devices.

After booting up I do not get a clock signal on SCLK pin. I do not get any recognized devices on SPI bus. But I can see that device support is available.

root@imx8mqevk:~# ls /sys/bus/spi/drivers
ds3234 m25p80 mcp251x mmc_spi mtd_dataflash spidev
root@imx8mqevk:~# ls /sys/bus/spi/devices/
root@imx8mqevk:~#

Re: CAN over SPI

Carlos_Musich — Thu, 19 Jul 2018 18:03:24 GMT

Hi Bastian,

you may find useful this document

Interfacing FXLS8471Q with i.MX6Q

Other useful threads will be

How to check if SPI is working?

Bringing spidev ioctl handlers to user space and running spidev_test app on imx6.

Regards,
Carlos
NXP Technical Support
-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

i.MX ProcessorsのトピックCAN over SPI

CAN over SPI

Re: CAN over SPI