3. CAN¶
3.1. Introduction¶
Controller area network (can) is a kind of serial communication network which can effectively support distributed control or real-time control. Can bus is a bus protocol widely used in automobile, which is designed as the communication of microcontroller in automobile environment.
3.2. Hardware Connection¶
Connection between two CAN devices, only need CAN_H to CAN_H, CAN_L to CAN_L.
3.3. DTS Configuration¶
Common
kernel-6.1/arch/arm64/boot/dts/rockchip/rv1126b.dtsican0: can@21d40000 { compatible = "rockchip,rv1126b-canfd"; reg = <0x21d40000 0x1000>; interrupts = <GIC_SPI 204 IRQ_TYPE_LEVEL_HIGH>; clocks = <&cru CLK_CAN0>, <&cru HCLK_CAN0>; clock-names = "baudclk", "apb_pclk"; resets = <&cru SRST_RESETN_CAN0>, <&cru SRST_HRESETN_CAN0>; reset-names = "can", "can-apb"; dmas = <&dmac 44>; dma-names = "rx"; status = "disabled"; }; can1: can@21d50000 { compatible = "rockchip,rv1126b-canfd"; reg = <0x21d50000 0x1000>; interrupts = <GIC_SPI 205 IRQ_TYPE_LEVEL_HIGH>; clocks = <&cru CLK_CAN1>, <&cru HCLK_CAN1>; clock-names = "baudclk", "apb_pclk"; resets = <&cru SRST_RESETN_CAN1>, <&cru SRST_HRESETN_CAN1>; reset-names = "can", "can-apb"; dmas = <&dmac 45>; dma-names = "rx"; status = "disabled"; };
Because there is only one CAN device created by the system according to the dts , and the first device created is CAN0.
3.4. Communication¶
3.4.1. CAN communication test¶
Use the “candump” and “cansend” tools directly to send and receive messages, push tool into /system/bin/ . Tools “candump/cansend” are included with the SDK and download from Officail link or github.
#Close the can0 device at the transceiver
ip link set can0 down
#Set the bit rate to 250Kbps at the transceiver
ip link set can0 type can bitrate 250000
#Show can0 details
ip -details link show can0
#Open the can0 device at the transceiver
ip link set can0 up
#Perform candump on the receiving end, blocking waiting for messages
candump can0
#Execute cansend at the sending end to send the message
cansend can0 123#1122334455667788
3.5. More Command¶
1、 ip link set canX down //turn off CAN device
2、 ip link set canX up //turn on CAN device
3、 ip -details link show canX //show CAN device details
4、 candump canX //Receive data from CAN bus
5、 ifconfig canX down //shutdown CAn device
6、 ip link set canX up type can bitrate 250000 //Set CAN Baudrate
7、 conconfig canX bitrate + (Baudrate)
8、 canconfig canX start //start CAN device
9、 canconfig canX ctrlmode loopback on //loopback test
10、canconfig canX restart //restart CAN device
11、canconfig canX stop //stop CAN device
12、canecho canX //check CAN device status查看can设备总线状态；
13、cansend canX --identifier=ID+data //send data
14、candump canX --filter=ID:mask //Use the filter to receive ID matching data