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

3. 硬件连接

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

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(*)

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）