文章目錄

目錄

文章目錄

前言

一、LIN總線是什么？

1.LIN總線的標準

2.LIN總線形式

3、幀的構成

二、UART模擬LIN從機的實現

1.方案概述

2.串口中斷處理

3、同步間隔斷中斷處理

4、接收中斷處理

驗證測試

1、CANoe IG發送幀頭

?2、示波器觀測波形

總結

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前言

在汽車領域，CAN總線和LIN總線是應用比較多的總線，因此需要對LIN總線有深入的了解。

本文主要梳理關鍵知識點，幫助大家建立整體的概念，重點在于知識體系的構建。

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一、LIN總線是什么？

1.LIN總線的標準

目前各大主機廠廣泛會用的是LIN2.1，波特率采用19200。

2.LIN總線形式

?LIN在總線上的展現形式，主機發幀頭（對比CAN的ID），從機響應數據（對比CAN的8字節數據）

3、幀的構成

?同步段為? 0x55

?ID段為? ? ?幀ID+校驗

數據段為? 幀的數據內容

校驗和? ? 數據段字節和ID的校驗和

二、UART模擬LIN從機的實現

1.方案概述

用接收中斷進行同步段驗證、數據接收

用發送中斷進行數據和校驗的發送

2.串口中斷處理

在中斷中處理

同步間隔中斷

接收中斷

發送中斷

void UartLIN_Handler(void *device, uint32_t wpara, uint32_t lpara) {// Receive break fieldif (0 != (lpara & UART_LSR1_FBRK_Msk)){LIN_IfcAux();UART_LIN->LSR1 |= UART_LSR1_FBRK_Msk; ///<write 1 to clear break status}// Receive dataif (0 != (wpara & UART_LSR0_DR_Msk)){LIN_IfcRx();}// Transmit data doneif (0 != (wpara & UART_LSR0_THRE_Msk)){LIN_IfcTx();} }

3、同步間隔斷中斷處理

void LIN_IfcAux(void) {if (g_mode == SLAVE_MODE){if (g_state == LIN_STATE_IDLE){g_state = g_autoBaud ? LIN_STATE_RECEIVE_IDENTIFIER : LIN_STATE_RECEIVE_SYNC;g_direction = DIR_RX;g_txCount = 0;g_rxCount = 0;USART_TXE_INT_Enable(USART1_SFR, FALSE);}else{//fprintf("Frame err\r\n");g_state = g_autoBaud ? LIN_STATE_RECEIVE_IDENTIFIER : LIN_STATE_RECEIVE_SYNC;g_direction = DIR_RX;g_txCount = 0;g_rxCount = 0;USART_TXE_INT_Enable(USART1_SFR, FALSE);}} }

4、接收中斷處理

void LIN_IfcRx(void) {uint8_t data = 0, id = 0, index = 0, checksum = 0, frameNum = 0;FRAME_ID_TBL *frameTable = 0, *frameInfo = 0;data = USART_ReceiveData(USART1_SFR);//fprintf("%02x ", data);if (g_direction == DIR_TX){ #if 0if (data != g_buffer[g_rxCount]){// Send error//fprintf("bit err\r\n");}g_rxCount++;// transmit doneif (g_rxCount == g_tranByte){frameInfo = &g_scheduleTable[g_schTblIdx].schedule[g_frameIdx];if (g_state == LIN_STATE_SEND_SYNC){// Start transmit or receive dataif (frameInfo->dir == DIR_TX){g_state = LIN_STATE_SEND_DATA;g_direction = DIR_TX;g_tranByte = frameInfo->dtl + 1;memcpy((void *)g_buffer, (const void *)frameInfo->data, (unsigned int)g_tranByte - 1);checksum = LIN_MakeChecksum((frameInfo->cst == ENHANCED_CHECKSUM) ? g_protectId : 0,frameInfo->dtl, frameInfo->data);g_buffer[g_tranByte - 1] = checksum;g_txCount = 0;g_rxCount = 0;//UART_SetTXEInterrupt(UART_LIN, ENABLE);USART_Send(USART1_SFR, g_buffer, g_tranByte);}else{g_state = LIN_STATE_RECEIVE_DATA;g_direction = DIR_RX;g_recvByte = frameInfo->dtl + 1;g_rxCount = 0;}}else if (g_state == LIN_STATE_SEND_DATA){// Transmit frame doneg_state = LIN_STATE_IDLE;}} #endif}else{if (g_mode == SLAVE_MODE){if (g_state == LIN_STATE_RECEIVE_SYNC){// Check sync fieldif (data == 0x55){g_state = LIN_STATE_RECEIVE_IDENTIFIER;}else{g_state = LIN_STATE_IDLE;//fprintf("Sync err\r\n");}}else if (g_state == LIN_STATE_RECEIVE_IDENTIFIER){// Check protect idid = data & 0x3F;if (data == LIN_MakeProtId(id)){frameTable = g_scheduleTable[g_schTblIdx].schedule;frameNum = g_scheduleTable[g_schTblIdx].frameNum;for (index = 0; index < frameNum; index++){frameInfo = &frameTable[index];// Find needed idif (id == frameInfo->id){g_frameIdx = index;g_protectId = data;//fprintf("%d\r\n", id);// Start transmit or receive dataif (frameInfo->dir == DIR_TX){g_state = LIN_STATE_SEND_DATA;g_direction = DIR_TX;g_tranByte = frameInfo->dtl + 1;memcpy((void *)g_buffer, (const void *)frameInfo->data, g_tranByte - 1);checksum = LIN_MakeChecksum((frameInfo->cst == ENHANCED_CHECKSUM) ? g_protectId : 0,frameInfo->dtl, frameInfo->data);g_buffer[g_tranByte - 1] = checksum;g_txCount = 0;g_rxCount = 0;//UART_SetTXEInterrupt(UART_LIN, ENABLE);//USART_Send(USART1_SFR, g_buffer, g_tranByte);USART_TXE_INT_Enable(USART1_SFR, TRUE);//delay_us(2);//g_state = LIN_STATE_IDLE;//g_direction = DIR_RX;//g_txCount = 0;//g_rxCount = 0;}else{g_state = LIN_STATE_RECEIVE_DATA;g_direction = DIR_RX;g_recvByte = frameInfo->dtl + 1;g_rxCount = 0;}break;}}// Not needed idif (index == frameNum){g_state = LIN_STATE_IDLE;//fprintf("Err Id:0x%x\r\n", data);}}else{g_state = LIN_STATE_IDLE;//fprintf("Pid:0x%x err\r\n", data);}}else if (g_state == LIN_STATE_RECEIVE_DATA){if (g_rxCount < g_recvByte){g_buffer[g_rxCount] = data;g_rxCount++;}// Receive frame doneif (g_rxCount == g_recvByte){frameInfo = &g_scheduleTable[g_schTblIdx].schedule[g_frameIdx];checksum = LIN_MakeChecksum((frameInfo->cst == ENHANCED_CHECKSUM) ? g_protectId : 0,g_recvByte - 1, g_buffer);if (checksum == g_buffer[g_rxCount - 1]){// Checksum is successful.// Save datamemcpy((void *)frameInfo->data, (const void *)g_buffer, g_rxCount - 1);}else{// Checksum is failed.//fprintf("Cs err\r\n");}g_state = LIN_STATE_IDLE;}}else{}}} }

發送中斷處理

void LIN_IfcTx(void) {if (g_direction == DIR_TX){if (g_mode == SLAVE_MODE){if (g_state == LIN_STATE_SEND_DATA){// Send dataif (g_txCount < g_tranByte){//UART_SendData(UART_LIN, g_buffer[g_txCount]);USART_SendData(USART1_SFR, g_buffer[g_txCount]);g_txCount++;if (g_txCount == g_tranByte){//UART_SetTXEInterrupt(UART_LIN, DISABLE);USART_TXE_INT_Enable(USART1_SFR, FALSE);}}else{//UART_SetTXEInterrupt(UART_LIN, DISABLE);USART_TXE_INT_Enable(USART1_SFR, FALSE);g_direction = DIR_RX;g_txCount = 0;g_rxCount = 0;}}else{//UART_SetTXEInterrupt(UART_LIN, DISABLE);USART_TXE_INT_Enable(USART1_SFR, FALSE);}}} }

數據結構和變量

typedef enum {LIN_STATE_IDLE, ///< Idle stateLIN_STATE_SEND_BREAK, ///< Send break stateLIN_STATE_RECEIVE_BREAK, ///< Receive break stateLIN_STATE_SEND_SYNC, ///< Send sync stateLIN_STATE_RECEIVE_SYNC, ///< Receive sync stateLIN_STATE_SEND_IDENTIFIER, ///< Send identifier stateLIN_STATE_RECEIVE_IDENTIFIER, ///< Receive identifier stateLIN_STATE_SEND_DATA, ///< Send data stateLIN_STATE_RECEIVE_DATA, ///< Receive data stateLIN_STATE_SEND_CHECKSUM, ///< Send checksum stateLIN_STATE_BUSSLEEP ///< Bus sleep state } lin_ifcState;typedef struct {uint8_t id; ///< LIN message frame ID for this frameuint8_t dir; ///< Name of the node that publishes the datauint8_t cst; ///< Type of checksum to be used (enhanced or classic)uint8_t dtl; ///< Number of bytes in the data fielduint16_t delayTime; ///< Actual slot time in ms for the frameuint8_t *data; ///< Address of the structure that lists the signals } FRAME_ID_TBL;typedef struct {uint8_t frameNum; ///< Number of frame slots in the schedule tableFRAME_ID_TBL *schedule; ///< Address of the schedule table } SCHEDULE_TBL;//#define UART_LIN UART1// Checksum type #define ENHANCED_CHECKSUM 0 ///< Enhanced checksum type #define CLASSIC_CHECKSUM 1 ///< Classic checksum type// Direction #define DIR_RX 0 ///< receive direction #define DIR_TX 1 ///< transmit direction// Node mode #define MASTER_MODE 0 ///< master mode #define SLAVE_MODE 1 ///< slave modeextern void LIN_IfcRx(void); extern void LIN_IfcAux(void); extern void LIN_IfcTx(void); extern void LinSlaveInit(void);void LinSlaveInit(void) {}uint8_t g_LinData[4][8] = {{0xA1,0xB2,0xC3,0xD4,0xE5,0xF6,0x97,0x88},{0x21,0x22,0x23,0x24,0x25,0x26,0x27,0x28},{0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08},{0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08}, };///< Master send header and receive data FRAME_ID_TBL g_frameTable1[] = {{0x23, 1, 0, 3, 60, g_LinData[0]},{0x21, 0, 0, 8, 60, g_LinData[1]} };///< Schedule table SCHEDULE_TBL g_scheduleTable[] = {{2, &g_frameTable1[0]} };uint32_t g_sendTimes = 0xFFFF; ///< Send frame timesuint8_t g_mode = SLAVE_MODE; ///< Master or slave mode uint8_t g_state = 0; ///< Lin state uint8_t g_schTblIdx = 0; ///< Schedule table index uint8_t g_frameIdx = 0; ///< Frame index uint8_t g_protectId = 0; ///< Protect id uint8_t g_firstFlag = 1; ///< First time flaguint8_t g_direction = 0; ///< Send direction uint8_t g_tranByte = 0; ///< Need transmit bytes uint8_t g_recvByte = 0; ///< Need receive bytes uint8_t g_txCount = 0; ///< Transmit data count uint8_t g_rxCount = 0; ///< Receive data count uint8_t g_autoBaud = 0; ///< Auto baud rate uint8_t g_breakThre = 1; ///< Break threshold uint8_t g_buffer[20] = {0}; ///< Data bufferuint8_t LIN_MakeProtId(uint8_t idData) {union {uint8_t byte;struct {uint8_t d0: 1;uint8_t d1: 1;uint8_t d2: 1;uint8_t d3: 1;uint8_t d4: 1;uint8_t d5: 1;uint8_t p0: 1;uint8_t p1: 1;} bit;} buf;/* Load the desired message frame ID into the LSBits of the buffer. */buf.byte = idData & (uint8_t)0x3F;/* Set the two parity bits. */buf.bit.p1 = ~(buf.bit.d1 ^ buf.bit.d3 ^ buf.bit.d4 ^ buf.bit.d5);buf.bit.p0 = buf.bit.d0 ^ buf.bit.d1 ^ buf.bit.d2 ^ buf.bit.d4;return buf.byte; }uint8_t LIN_MakeChecksum(uint8_t protectId, uint8_t length, uint8_t *data) {uint8_t i = 0, checksum = 0;uint16_t sum = protectId;for (i = 0; i < length; i++){sum += data[i];if (sum >= 0x100){sum -= 0xFF;}}checksum = ~(uint8_t)sum;return checksum; }

驗證測試

1、CANoe IG發送幀頭

?2、示波器觀測波形

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總結

利用串口可以完美模擬從機，發送和接收采用中斷的形式有利于提高程序的執行效率。

5.1的最后一天假，完美收官

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