PIC32 & MPLAB IDE学习笔记之CAN

1万 · 2021-9-6 16:21

CAN
34.1 简介

34.7 发送CAN报文
每个报文需要占用4个双字(16个字节)数据的缓存区RAM

34.8 接收报文过滤
过滤器为需要相同匹配位，屏蔽器为屏蔽匹配位。

1万 · 2021-9-6 16:23

实例1：比较所有位，只接收帧ID为0x8004001的扩展帧

/* Step 5: Configure filters and mask. Configure
   * filter 0 to accept EID messages with ID 0x8004001.
   * Configure filter mask 0 to compare all the ID
   * bits and to filter by the ID type specified in
   * the filter configuration.Messages accepted by
   * filter 0 should be stored in channel 1. */

CANConfigureFilter    (CAN1, CAN_FILTER0, 0x8004001, CAN_EID);
CANConfigureFilterMask  (CAN1, CAN_FILTER_MASK0, 0x3FFFFFFF, CAN_EID, CAN_FILTER_MASK_IDE_TYPE);
CANLinkFilterToChannel  (CAN1, CAN_FILTER0, CAN_FILTER_MASK0, CAN_CHANNEL1);
CANEnableFilter       (CAN1, CAN_FILTER0, TRUE);

实例2：屏蔽所有位，接收所有帧数据

CANConfigureFilter    (CAN1, CAN_FILTER0, 0x1FFFFFFF, CAN_EID);
CANConfigureFilterMask  (CAN1, CAN_FILTER_MASK0, 0x00000000, CAN_EID, CAN_FILTER_MASK_IDE_TYPE);
CANLinkFilterToChannel  (CAN1, CAN_FILTER0, CAN_FILTER_MASK0, CAN_CHANNEL1);
CANEnableFilter       (CAN1, CAN_FILTER0, TRUE);

1万 · 2021-9-6 16:24

二、初始化

#define configCPU_CLOCK_HZ (80000000UL) //80M
#define CAN_BUS_SPEED 250000 //250k
#define CAN1_FIFO_Numb 2 // 配置2块FIFO自动缓冲区
#define CAN_FIFO_LENG 32 // 每个FIFO配置32个报文
#define CAN_FRAM_SIZE 16 // 每个报文占有16字节

void CanInit(UINT canNo)
{
      CAN_BIT_CONFIG canBitConfig;

CANEnableModule(CAN1,TRUE); //使能CAN1

CANSetOperatingMode(CAN1, CAN_CONFIGURATION); //配置模式
while(CANGetOperatingMode(CAN1) != CAN_CONFIGURATION); //配置模式确认

canBitConfig.phaseSeg2Tq          = CAN_BIT_3TQ; //相位缓冲段2
canBitConfig.phaseSeg1Tq          = CAN_BIT_3TQ;  //相位缓冲段1
canBitConfig.propagationSegTq    = CAN_BIT_3TQ; //传播时间段
canBitConfig.phaseSeg2TimeSelect = TRUE; //阶段2       TRUE代码指定，FALSE模块自动设置
canBitConfig.sample3Time          = TRUE; //bit被采样次数，TRUE 3次，FALSE 1次
      canBitConfig.syncJumpWidth       = CAN_BIT_2TQ; //同步段
      CANSetSpeed(CAN1,&canBitConfig,configCPU_CLOCK_HZ,CAN_BUS_SPEED); //设置CAN总线波特率

//分配缓存区，2个FIFO,每个FIFO有32个报文，每个报文16个字节
CANAssignMemoryBuffer(CAN1,CAN1MessageFifoArea,(CAN1_FIFO_Numb *CAN_FIFO_LENG *CAN_FRAM_SIZE)); //分配缓存区 2*32*16

//FIFO0配置为发送帧，FIFO1配置为接收帧
      CANConfigureChannelForTx(CAN1, CAN_CHANNEL0, CAN_FIFO_LENG, CAN_TX_RTR_ENABLED, CAN_LOW_MEDIUM_PRIORITY); //FIFO0配置为发射远程帧，低中优先级
      CANConfigureChannelForRx(CAN1, CAN_CHANNEL1, CAN_FIFO_LENG, CAN_RX_FULL_RECEIVE); //FIFO0配置为数据全接收（ID+Data）

//配置屏蔽器屏蔽所有位，FIFO0接收所有帧
     CANConfigureFilter    (CAN1, CAN_FILTER0, 0x1FFFFFFF, CAN_SID); //过滤器0配置
      CANConfigureFilterMask  (CAN1, CAN_FILTER_MASK0, 0x00000000, CAN_EID, CAN_FILTER_MASK_ANY_TYPE);//屏蔽器0配置为扩展帧/所有数据
      CANLinkFilterToChannel  (CAN1, CAN_FILTER0, CAN_FILTER_MASK0, CAN_CHANNEL1); //过滤器0、屏蔽器0、FIFO0匹配
      CANEnableFilter       (CAN1, CAN_FILTER0, TRUE); //使能过滤器0

      CANEnableChannelEvent(CAN1, CAN_CHANNEL1, CAN_RX_CHANNEL_NOT_EMPTY, TRUE); //打开接收非空中断
      CANEnableModuleEvent (CAN1, CAN_RX_EVENT, TRUE); //打开接收中断

      INTSetVectorPriority(INT_CAN_1_VECTOR, INT_PRIORITY_LEVEL_3); //中断优先级 3
      INTSetVectorSubPriority(INT_CAN_1_VECTOR, INT_SUB_PRIORITY_LEVEL_0); //子优先级 0
      INTEnable(INT_CAN1, INT_ENABLED); //中断使能

CANSetOperatingMode(CAN1, CAN_NORMAL_OPERATION); //正常工作模式
while(CANGetOperatingMode(CAN1) != CAN_NORMAL_OPERATION); //正常工作模式确认
}