GPIO pin configuration issue for UART communication

General
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21

I found the issue: the interrupt pins defined in the overlay DTS were different at both locations. The correct DTS for the overlays is

/dts-v1/;
/plugin/;

#include <dt-bindings/gpio/gpio.h>
#include <dt-bindings/pinctrl/rockchip.h>
#include <dt-bindings/interrupt-controller/irq.h>

&{/} {
    metadata {
        title ="Enable SPI2 MCP2515 (CAN) support on 40 Pin GPIO Header";
        compatible = "vicharak,rk3399-axon", "rockchip,rk3399";
        category = "misc";
        exclusive = "spi2", "GPIO2_B1", "GPIO2_B2", "GPIO2_B3", "GPIO2_B4",
				"GPIO4_D6";
        description = "Enable MCP2515 on SPI2 with 12 MHz Crystal Oscillator.
INT=22";
    };

	can_mcp2515_osc: can-mcp2515-osc {
		status = "okay";
		compatible = "fixed-clock";
		clock-frequency = <12000000>;
		#clock-cells = <0>;
	};
};

&pinctrl {
	mcp2515_int_pin {
		mcp2515_int_pin: mcp2515_int_pin {
			rockchip,pins = <4 RK_PD6 RK_FUNC_GPIO &pcfg_pull_none>;
		};
	};
};

&spi2 {
	status = "okay";
	#address-cells = <1>;
	#size-cells = <0>;

	can_mcp2515: can-mcp2515@0 {
		status = "okay";
		compatible = "microchip,mcp2515";
		reg = <0>;
		interrupt-parent = <&gpio4>;
		interrupts = <RK_PD6 IRQ_TYPE_EDGE_FALLING>;
		spi-max-frequency = <10000000>;
		clocks = <&can_mcp2515_osc>;
		vdd-supply = <&vcc3v3_sys>;
		xceiver-supply = <&vcc3v3_sys>;
		pinctrl-names = "default";
		pinctrl-0 = <&mcp2515_int_pin>;
	};
};

Another important point is that you must connect the pins correctly and provide the proper power supply as mentioned in the IC’s documentation. Any incorrect pin connection will cause errors when probing the MCP251x driver.

If you face any problems, please let me know.

22

For pin documentation, you can refer to this.
https://docs.vicharak.in/vicharak_sbcs/vaaman/vaaman-gpio-description/#vaaman-gpio-description

23

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image878×422 26.5 KB

I have connected the MCP2525 IC pins to Vicharak GPIO as follows:

  1. CAN2_MOSI → GPIOT_RXN27
  2. CAN2_MISO → GPIOR_174
  3. CAN2_CS → GPIOT_RXP27
  4. CAN2_SCK → GPIOR_173
    Where should I connect CAN2_INT (to which GPIO)?
24

Hello @Avi_Shihora @vatsal any updates on this

25

You are testing the MCP2515 IC using the SoC GPIOs Header, so your pin connections should be as follows:

  • INT → GPIO4_D6 → Pin 37 on SoC
  • SCK → GPIO2_B3 → Pin 7 on SoC
  • MOSI → GPIO2_B2 → Pin 29 on SoC
  • MISO → GPIO2_B1 → Pin 31 on SoC
  • CS → GPIO2_B4 → Pin 33 on SoC

For your reference, all of these pins are already defined in the DTS overlays for SPI2 on the processor.

Please note that the pins GPIOT_RXN27, GPIOR_174, GPIOT_RXP27, and GPIOR_173 are FPGA pins. These are only useful when working with Periplex. They are not used when running applications directly on the SoC (processor).

For Soc pinout guide , Documentation references : Vaaman GPIO Description | Vicharak

For FPGA pinout guide , Documentation references : documentaion:Vaaman GPIO Description | Vicharak

Refer this pdf for more information : https://docs.vicharak.in/_static/files/Vaaman0.3_Pinout_Guide_Rev0.3.pdf

26

Thank you, I will use the SoC GPIO header pins and check.

27
  1. I used the following DTSO file:

/dts-v1/;
/plugin/;

#include <dt-bindings/gpio/gpio.h>
#include <dt-bindings/pinctrl/rockchip.h>
#include <dt-bindings/interrupt-controller/irq.h>

&{/} {
metadata {
title =“Enable SPI2 MCP2515 (CAN) support on 40 Pin GPIO Header”;
compatible = “vicharak,rk3399-axon”, “rockchip,rk3399”;
category = “misc”;
exclusive = “spi2”, “GPIO2_B1”, “GPIO2_B2”, “GPIO2_B3”, “GPIO2_B4”,
“GPIO4_D6”;
description = “Enable MCP2515 on SPI2 with 12 MHz Crystal Oscillator. INT=22”;
};

can_mcp2515_osc: can-mcp2515-osc {
    status = "okay";
    compatible = "fixed-clock";
    clock-frequency = <12000000>;
    #clock-cells = <0>;
};

};

&pinctrl {
mcp2515_int_pin {
mcp2515_int_pin: mcp2515_int_pin {
rockchip,pins = <4 RK_PD6 RK_FUNC_GPIO &pcfg_pull_none>;
};
};
};

&spi2 {
status = “okay”;
#address-cells = <1>;
#size-cells = <0>;

can_mcp2515: can-mcp2515@0 {
    status = "okay";
    compatible = "microchip,mcp2515";
    reg = <0>;
    interrupt-parent = <&gpio4>;
    interrupts = <RK_PD6 IRQ_TYPE_EDGE_FALLING>;
    spi-max-frequency = <10000000>;
    clocks = <&can_mcp2515_osc>;
    vdd-supply = <&vcc3v3_sys>;
    xceiver-supply = <&vcc3v3_sys>;
    pinctrl-names = "default";
    pinctrl-0 = <&mcp2515_int_pin>;
};

};

  1. After that, I ran the following commands:

cpp -nostdinc -undef -x assembler-with-cpp -E
-I /usr/src/linux-headers-$(uname -r)/include
-I /usr/lib/modules/$(uname -r)/build/include
rk3399-vaaman-spi2-mcp2515.dtso -o rk3399-vaaman-spi2-mcp2515.dtsi

dtc -I dts -O dtb rk3399-vaaman-spi2-mcp2515.dtsi -o rk3399-vaaman-spi2-mcp2515.dtbo

sudo cp rk3399-vaaman-spi2-mcp2515.dtbo /boot/overlays-$(uname -r)/

sudo u-boot-update

sudo reboot

  1. After rebooting, I checked with the following commands, but can0 was not showing up:

dmesg | grep mcp2515

ls /dev/spidev*

Output:

/dev/spidev0.0 /dev/spidev2.0

ip link | grep can

28

What is the dmesg log when you insert the mcp251x.ko module? Please provide it as a file named dmesg.txt by running the following command:

sudo dmesg > dmesg.txt

29

dmesg.txt (45.7 KB)

30

Please check the dmesg file

31

First, insert the mcp251x.ko module the same way you did before. After that, I will check the dmesg log to identify the error you faced during insmod. You have done this step in the past, so please insert the module manually and then send me the dmesg log, because right now I don’t see any messages related to mcp251x in your dmesg

32

Okay I will check it again and let you know