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CAN 使用

1. CAN 简介​

CAN (controller Area Network)：控制器局域网络总线，是一种有效支持分布式控制或实时控制的串行通信网络。

  • 目前世界上绝大多数汽车制造厂商都采用CAN总线来实现汽车内部控制系统之间的数据通信。

  • RK3568/RK3588的CAN驱动文件：drivers/net/can/rockchip/rockchip_canfd.c

  • 在ArmSoM-Sige7中，CAN集成在40PIN中，可供用户复用为CAN相关引脚。

2. 原理图​

CAN在40PIN中的位置: CAN_TX对应40PIN中的第35编号，CAN_RX对应40PIN中的第12编号 can-sch

3. 硬件连接​

CAN模块之间接线：CAN_TX接CAN_TX，CAN_RX接CAN_RX。

can-real

4. 内核配置​

  • rockchip_linux_defconfig配置：
CONFIG_CAN=y

CONFIG_CAN_DEV=y

CONFIG_CAN_ROCKCHIP=y

CONFIG_CANFD_ROCKCHIP=y
  • 内核配置：
cd kernel

make ARCH=arm64 menuconfig

make savedefconfig
  • 选择：Networking support ---> CAN bus subsystem support ()--->CAN Device Drivers() ---> Platform CAN drivers with Netlink support(*)

can-config

5. DTS 节点配置​

5.1 主要参数:​

  • interrupts 转换完成，产生中断信号。

  • clock 时钟属性，用于驱动开关clk，reset属性，用于每次复位总线。

  • pinctrl 配置CAN相关的引脚信息，功能复用

5.2 芯片级公共配置​

kernel-5.10/arch/arm64/boot/dts/rockchip/rk3588s.dtsi

can0: can@fea50000 {
                compatible = "rockchip,can-2.0";
                reg = <0x0 0xfea50000 0x0 0x1000>;
                interrupts = <GIC_SPI 341 IRQ_TYPE_LEVEL_HIGH>;
                clocks = <&cru CLK_CAN0>, <&cru PCLK_CAN0>;
                clock-names = "baudclk", "apb_pclk";
                resets = <&cru SRST_CAN0>, <&cru SRST_P_CAN0>;
                reset-names = "can", "can-apb";
                pinctrl-names = "default";
                pinctrl-0 = <&can0m0_pins>;
                tx-fifo-depth = <1>;
                rx-fifo-depth = <6>;
                status = "disabled";
        };
    
can1: can@fea60000 {
                compatible = "rockchip,can-2.0";
                reg = <0x0 0xfea60000 0x0 0x1000>;
                interrupts = <GIC_SPI 342 IRQ_TYPE_LEVEL_HIGH>;
                clocks = <&cru CLK_CAN1>, <&cru PCLK_CAN1>;
                clock-names = "baudclk", "apb_pclk";
                resets = <&cru SRST_CAN1>, <&cru SRST_P_CAN1>;
                reset-names = "can", "can-apb";
                pinctrl-names = "default";
                pinctrl-0 = <&can1m0_pins>;
                tx-fifo-depth = <1>;
                rx-fifo-depth = <6>;
                status = "disabled";
        };
    
can2: can@fea70000 {
                compatible = "rockchip,can-2.0";
                reg = <0x0 0xfea70000 0x0 0x1000>;
                interrupts = <GIC_SPI 343 IRQ_TYPE_LEVEL_HIGH>;
                clocks = <&cru CLK_CAN2>, <&cru PCLK_CAN2>;
                clock-names = "baudclk", "apb_pclk";
                resets = <&cru SRST_CAN2>, <&cru SRST_P_CAN2>;
                reset-names = "can", "can-apb";
                pinctrl-names = "default";
                pinctrl-0 = <&can2m0_pins>;
                tx-fifo-depth = <1>;
                rx-fifo-depth = <6>;
                status = "disabled";
        };

  • compatible = “rockchip,can-1.0” ，rockchip,can-1.0用来匹配can控制器驱动。

  • compatible = “rockchip,can-2.0” ，rockchip,can-2.0用来匹配canfd控制器驱动。

  • assigned-clock-rates用来配置can的始终频率，如果CAN的比特率低于等于3M建议修改CAN时钟到100M，信号更稳定。高于3M比特率的，时钟设置200M就可以。

  • pinctrl配置：根据实际板卡连接情况配置can_h和can_l的iomux作为can功能使用。

5.3 板级配置​

kernel-5.10/arch/arm64/boot/dts/rockchip/rk3588-armsom-w3.dts

/* can1 */
&can1 {
        status = "okay";
        assigned-clocks = <&cru CLK_CAN1>;
        assigned-clock-rates = <200000000>;
        pinctrl-names = "default";
        pinctrl-0 = <&can1m1_pins>;      #根据原理图进行配置
};
  • 由于系统根据上述dts节点创建的CAN设备只有一个，而第一个创建的设备为CAN0

6. CAN通信测试​

  • 查询当前⽹络设备:
ifconfig -a
  • CAN启动
ip link set can0 down   //关闭CAN

ip link set can0 type can bitrate 500000   #设置⽐特率500KHz

ip -details -statistics link show can0    #打印can0信息
    
ip link set can0 up     //启动CAN
  • CAN发送
cansend can0 123#DEADBEEF            #发送（标准帧,数据帧,ID:123,date:DEADBEEF）

cansend can0 123#R                   #发送（标准帧,远程帧,ID:123）
    
cansend can0 00000123#12345678       #发送（扩展帧,数据帧,ID:00000123,date:DEADBEEF）

cansend can0 00000123#R              #发送（扩展帧,远程帧,ID:00000123）
  • CAN接收
candump can0       //candump can0