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。
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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。
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RK3568/RK3588的CAN驱动文件：drivers/net/can/rockchip/rockchip_canfd.c
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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=yCONFIG_CAN_DEV=yCONFIG_CAN_ROCKCHIP=yCONFIG_CANFD_ROCKCHIP=y
- 内核配置：
cd kernelmake ARCH=arm64 menuconfigmake 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:
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interrupts = <GIC_SPI 1 IRQ_TYPE_LEVEL_HIGH>;
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";};
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compatible = “rockchip,can-1.0” ，rockchip,can-1.0用来匹配can控制器驱动。
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compatible = “rockchip,can-2.0” ，rockchip,can-2.0用来匹配canfd控制器驱动。
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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。
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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CANip link set can0 type can bitrate 500000 #设置⽐特率500KHzip -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#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
