瑞薩RA2L1系列MCU簡(jiǎn)介

RA2L1產(chǎn)品組基于Arm Cortex-M23 核心（現(xiàn)今 Arm Cortex-M系列中功耗最低的 CPU）。這款產(chǎn)品采用優(yōu)化的制程和瑞薩電子的低功耗工藝技術(shù)，是業(yè)界一流水平的超低功耗微控制器。RA2L1產(chǎn)品組能夠支持1.6V至5.5V寬電壓工作，CPU時(shí)鐘頻率最高48MHz，且運(yùn)行模式電流和待機(jī)模式電流更低。RA2L1產(chǎn)品群配備了增強(qiáng)型電容式觸摸感應(yīng)單元（CTSU2）、CAN控制器局域網(wǎng)總線，串行通信接口、高精度模擬電路和定時(shí)器。產(chǎn)品封裝從48引腳到100引腳。

一控制器局域網(wǎng)CAN模塊簡(jiǎn)介

控制器局域網(wǎng)（CAN）模塊使用基于消息的協(xié)議在電磁噪聲應(yīng)用中的多個(gè)從機(jī)和主機(jī)之間接收和傳輸數(shù)據(jù)。

該模塊符合ISO11898-1(CAN2.0A / CAN2.0B)標(biāo)準(zhǔn)，最多支持32個(gè)郵箱，可配置為普通郵箱和FIFO模式下的發(fā)送或接收。支持標(biāo)準(zhǔn)（11位）和擴(kuò)展（29位）消息格式。CAN模塊需要額外的外部CAN收發(fā)器。

CAN模塊框圖

注意事項(xiàng)：

CAN需要外部高速晶體作為時(shí)鐘源，使用CAN模塊前需要先配置好外部高速時(shí)鐘。

CAN模塊參數(shù)規(guī)格

二RA2L1 CAN通信應(yīng)用例程

使用官方e2 studio開發(fā)工具創(chuàng)建RA2L1工程，并添加CAN外設(shè)模塊底層應(yīng)用。

配置CAN模塊參數(shù)（包括通信速率、引腳配置等）。

三CAN應(yīng)用參考代碼

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#define WAIT_TIME            (500U)       //wait time value
#define CAN_MAILBOX_NUMBER_TX      (0U)        //mail box number
#define CAN_MAILBOX_NUMBER_RX      (1U)
#define CAN_FRAME_TRANSMIT_DATA_BYTES  (8U)        //data length
#define ZERO              (0U)


/* Private global variables*/
/* Flags, set from Callback function */
static volatile bool b_can_tx = false;         //CAN transmission status
static volatile bool b_can_rx = false;         //CAN receive status
static volatile bool b_can_err = false;         //CAN error status
/* CAN frames for tx and rx */
static can_frame_t g_can_tx_frame;           //CAN transmit frame
static can_frame_t g_can_rx_frame;           //CAN receive frame


void hal_entry(void)
{
  /* TODO: add your own code here */
  fsp_err_t err = FSP_SUCCESS;
  uint32_t time_out = WAIT_TIME;                   // time out
  uint8_t can_tx_msg[CAN_FRAME_TRANSMIT_DATA_BYTES] = {0,1,2,3,4,5,6,7};
  uint8_t can_rx_msg[CAN_FRAME_TRANSMIT_DATA_BYTES] = {0};


  /* Initializes the CGC module. */
  err = R_CGC_Open(&g_cgc0_ctrl, &g_cgc0_cfg);
  /* Handle any errors. This function should be defined by the user. */
  assert(FSP_SUCCESS == err);


  /* Start the CGC_CLOCK_MAIN_OSC. */
  err = R_CGC_ClockStart(&g_cgc0_ctrl, CGC_CLOCK_MAIN_OSC, NULL);
  assert(FSP_SUCCESS == err);


  /* Initialize CAN module */
  err = R_CAN_Open(&g_can_ctrl, &g_can_cfg);
  /* Error trap */
  if(FSP_SUCCESS != err)
  {
    __asm("BKPT #0
");
  }
  g_can_tx_frame.id = CAN_MAILBOX_NUMBER_TX;
  g_can_tx_frame.type = CAN_FRAME_TYPE_DATA;
  g_can_tx_frame.data_length_code = CAN_FRAME_TRANSMIT_DATA_BYTES;


  /* copy the tx data frame with TX_MSG */
  memcpy((uint8_t*)&g_can_tx_frame.data[ZERO], (uint8_t*)&can_tx_msg[ZERO], CAN_FRAME_TRANSMIT_DATA_BYTES);
  err = R_CAN_Write(&g_can_ctrl, CAN_MAILBOX_NUMBER_TX, &g_can_tx_frame);
  /* Error trap */
  if (FSP_SUCCESS != err)
  {
    err = R_CAN_Close(&g_can_ctrl);
    if (FSP_SUCCESS != err)
    {
      __asm("BKPT #0
");
    }
  }


  while(1)
  {
    /* check if receive flag is set */
    if (true == b_can_rx)
    {
      /* Reset flag bit */
      b_can_rx = false;


      g_can_rx_frame.data[CAN_FRAME_TRANSMIT_DATA_BYTES-1] = g_can_rx_frame.id;


      /* Transmit the rx data frame as acknowledging the data transfer is successful */
      err = R_CAN_Write (&g_can_ctrl, CAN_MAILBOX_NUMBER_TX, &g_can_rx_frame);
      /* Error trap */
      if (FSP_SUCCESS != err)
      {
        err = R_CAN_Close(&g_can_ctrl);
        if (FSP_SUCCESS != err)
        {
          __asm("BKPT #0
");
        }
      }
      /* wait for transmit flag bit to set */
      while ((true != b_can_tx) && (time_out--));
      if (0 == time_out)
      {
        __asm("BKPT #0
");
      }
      /* Reset flag bit */
      b_can_tx = false;
    }
  }
}


void can_callback(can_callback_args_t *p_args)
{
  switch (p_args->event)
  {
    case CAN_EVENT_TX_COMPLETE:
    {
      b_can_tx = true;    //set flag bit
      break;
    }


    case CAN_EVENT_RX_COMPLETE:
    {
      b_can_rx = true;
//copy the received data to rx_frame
  memcpy(&g_can_rx_frame, p_args->p_frame, sizeof(can_frame_t));       break;
    }


    case CAN_EVENT_MAILBOX_MESSAGE_LOST:  //overwrite/overrun error event
    case CAN_EVENT_BUS_RECOVERY:      //Bus recovery error event
    case CAN_EVENT_ERR_BUS_OFF:       //error Bus Off event
    case CAN_EVENT_ERR_PASSIVE:       //error passive event
    case CAN_EVENT_ERR_WARNING:       //error warning event
    {
      b_can_err = true;          //set flag bit
      break;
    }
  }
}

四CAN通信實(shí)測(cè)驗(yàn)證

RA2L1芯片內(nèi)部只有CAN控制器，需要與外部CAN設(shè)備通信時(shí)，還需要外接CAN收發(fā)器。

CAN收發(fā)器應(yīng)用參考原理圖

使用USB-CAN工具測(cè)試CAN通信

a. 接收不到ID為0的數(shù)據(jù)

b. 禁止Mask功能后，可接收所有ID的數(shù)據(jù).

審核編輯：湯梓紅