瑞薩RA2L1系列CAN通信應(yīng)用

RA2L1產(chǎn)品組基于ArmCortex-M23 核心（現(xiàn)今 ArmCortex-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器。產(chǎn)品封裝從48引腳到100引腳。

控制器局域網(wǎng)CAN模塊簡介

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

CAN模塊參數(shù)規(guī)格

RA2L1 CAN通信應(yīng)用例程

使用官方e2studio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）。

CAN應(yīng)用參考代碼

#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\n"); } 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\n"); } } 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\n"); } } /* wait for transmit flag bit to set */ while ((true != b_can_tx) && (time_out--)); if (0 == time_out) { __asm("BKPT #0\n"); } /* 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; } } }

CAN通信實(shí)測驗證

RA2L1芯片內(nèi)部只有CAN控制器，需要與外部CAN設(shè)備通信時，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).