LIN总线解析与UART模拟LIN从机实战
2024-05-13 04:05:48
文章目录
目录
文章目录
前言
一、LIN总线是什么？
1.LIN总线的标准
2.LIN总线形式
3、帧的构成
二、UART模拟LIN从机的实现
1.方案概述
2.串口中断处理
3、同步间隔断中断处理
4、接收中断处理
验证测试
1、CANoe IG发送帧头
2、示波器观测波形
总结
前言
在汽车领域，CAN总线和LIN总线是应用比较多的总线，因此需要对LIN总线有深入的了解。
本文主要梳理关键知识点，帮助大家建立整体的概念，重点在于知识体系的构建。
一、LIN总线是什么？
1.LIN总线的标准
目前各大主机厂广泛会用的是LIN2.1，波特率采用19200。
2.LIN总线形式
LIN在总线上的展现形式，主机发帧头（对比CAN的ID），从机响应数据（对比CAN的8字节数据）
3、帧的构成
同步段为 0x55
ID段为 帧ID+校验
数据段为 帧的数据内容
校验和 数据段字节和ID的校验和
二、UART模拟LIN从机的实现
1.方案概述
用接收中断进行同步段验证、数据接收
用发送中断进行数据和校验的发送
2.串口中断处理
在中断中处理
同步间隔中断
接收中断
发送中断
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、同步间隔断中断处理
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、接收中断处理
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{}}}
}发送中断处理
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);}}}
}数据结构和变量
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;
}验证测试
1、CANoe IG发送帧头
2、示波器观测波形
总结
利用串口可以完美模拟从机，发送和接收采用中断的形式有利于提高程序的执行效率。
5.1的最后一天假，完美收官
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