[经验]

基于MM32F5270开发板实现FLEXCAN模块发送

2022-8-29 14:59:17

2881 缓冲器 RAM

flexcan

FlexCAN 模块是 CAN 协议的一个高完成度版本，带有动态数据率（Flexible Data rate，CAN FD）协议和 CAN 2.0 B 版本协议，支持标准和拓展数据帧和长达 64 字节的数据传输，频率最大可达到 8Mbps。数据缓冲器存在于中一个嵌入FlexCAN的 RAM 中。

参考例程

title=

烧入该程序后使用can会出现以下情况：

该程序的位时序计算有点小bug，相位缓冲区1和2等参数不需要改变，把波特率从1M改成500k即可正常使用500k，其他需求请另外计算

一.时钟，引脚，串口通讯初始化

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二.CAN1配置

void app_flexcan_init(void)

{

/* Set the baudrate and bit time. */
FLEXCAN_TimConf_Type flexcan_tim_conf;
flexcan_tim_conf.EnableExtendedTime = true;
flexcan_tim_conf.PhaSegLen1 = 2u;
flexcan_tim_conf.PhaSegLen2 = 1u;
flexcan_tim_conf.PropSegLen = 1u;
flexcan_tim_conf.JumpWidth = 1u;

/* Setup FlexCAN. */
FLEXCAN_Init_Type flexcan_init;
flexcan_init.MaxXferNum = APP_FLEXCAN_XFER_MaxNum; /* The max mb number to be used. */
flexcan_init.ClockSource = FLEXCAN_ClockSource_Periph; /* Use peripheral clock. */
flexcan_init.BaudRate = APP_FLEXCAN_XFER_BAUDRATE; /* Set baudrate. */
flexcan_init.ClockFreqHz = BOARD_FLEXCAN_CLOCK_FREQ; /* Set clock frequency. */
flexcan_init.SelfWakeUp = FLEXCAN_SelfWakeUp_BypassFilter; /* Use unfiltered signal to wake up flexcan. */
flexcan_init.WorkMode = FLEXCAN_WorkMode_Normal; /* Normal workmode, can receive and transport. */
flexcan_init.Mask = FLEXCAN_Mask_Global; /* Use global mask for filtering. */
flexcan_init.EnableSelfReception = false; /* Not receiving mb frame sent by self. */
flexcan_init.EnableTimerSync = true; /* Every tx or rx done, refresh the timer to start from zero. */
flexcan_init.TimConf = &flexcan_tim_conf; /* Set timing sychronization. */
FLEXCAN_Init(BOARD_FLEXCAN_PORT, &flexcan_init);

/* Set tx mb. */
FLEXCAN_ResetMb(BOARD_FLEXCAN_PORT, BOARD_FLEXCAN_TX_MB_CH);
FLEXCAN_SetMbCode(BOARD_FLEXCAN_PORT, BOARD_FLEXCAN_TX_MB_CH, FLEXCAN_MbCode_TxInactive);

/* Enable intterupts for tx mb. */
FLEXCAN_EnableMbInterrupts(BOARD_FLEXCAN_PORT, BOARD_FLEXCAN_TX_MB_INT, true);
NVIC_EnableIRQ(BOARD_FLEXCAN_IRQn);

}

三.can1发送函数

void app_flexcan_tx(uint8_t * tx_buf)

{

FLEXCAN_Mb_Type mb;
mb.ID = APP_FLEXCAN_XFER_ID; /* Indicated ID number. */
mb.TYPE = FLEXCAN_MbType_Data; /* Data frame type. */
mb.FORMAT = FLEXCAN_MbFormat_Standard; /* STD frame format. */
mb.PRIORITY = APP_FLEXCAN_XFER_PRIORITY; /* The priority of the frame mb. */

/* Set the information. */
mb.BYTE0 = tx_buf[0];
mb.BYTE1 = tx_buf[1];
mb.BYTE2 = tx_buf[2];
mb.BYTE3 = tx_buf[3];
mb.BYTE4 = tx_buf[4];
mb.BYTE5 = tx_buf[5];
mb.BYTE6 = tx_buf[6];
mb.BYTE7 = tx_buf[7];

/* Set the workload size. */
mb.LENGTH = APP_FLEXCAN_XFER_BUF_LEN;

/* Send. */
FLEXCAN_WriteTxMb(BOARD_FLEXCAN_PORT, BOARD_FLEXCAN_TX_MB_CH, &mb);
FLEXCAN_SetMbCode(BOARD_FLEXCAN_PORT, BOARD_FLEXCAN_TX_MB_CH, FLEXCAN_MbCode_TxDataOrRemote); /* Write code to send. */

}

四.main函数

int main(void)

{

BOARD_Init();
printf("

flexcan_b2b_tx example.

");

/* Setup the flexcan module.*/
app_flexcan_init();
printf("press any key to send frame with id %u

", (unsigned)APP_FLEXCAN_XFER_ID);

while (1)
{  

    /* Send a message through flexcan. */
    for(uint8_t i = 0u;i<8;i++)
    {
     app_flexcan_tx_buf[i]=0;  //发送数据随意修改
     printf("%u ", (unsigned)app_flexcan_tx_buf[i]);
    }
    printf("app_flexcan_tx() sending: ");
    
    printf("

");


    app_flexcan_tx(app_flexcan_tx_buf);

    /* Wait for reception. */
    while (!app_flexcan_tx_flag) /* This flag will be on when the Tx interrupt is asserted. */
    {
    }
    app_flexcan_tx_flag = false;
    printf("app_flexcan_tx() done.



");
}