【MM32F5270开发板试用】flexcan\_b2b\_tx
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
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
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("\r\nflexcan_b2b_tx example.\r\n");
/* Setup the flexcan module.*/
app_flexcan_init();
printf("press any key to send frame with id %u\r\n", (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("\r\n");
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.\r\n\r\n");
}}
五.使用can分析仪查看效果
总结：
程序框架封装很好，该芯片比市面上常用M3，M4内核快30%，功能强大
下一篇文章准备使用can协议M3508无刷电机速度，位置闭环
