自定義串口通信協(xié)議，如何實(shí)現(xiàn)？
作者 | strongerHuang
微信公眾號(hào) | 嵌入式專欄
1什么通信協(xié)議？
通信協(xié)議是指雙方實(shí)體完成通信或服務(wù)所必須遵循的規(guī)則和約定。通過(guò)通信信道和設(shè)備互連起來(lái)的多個(gè)不同地理位置的數(shù)據(jù)通信系統(tǒng)，要使其能協(xié)同工作實(shí)現(xiàn)信息交換和資源共享，它們之間必須具有共同的語(yǔ)言。交流什么、怎樣交流及何時(shí)交流，都必須遵循某種互相都能接受的規(guī)則。這個(gè)規(guī)則就是通信協(xié)議。
| 幀頭 | 溫度值 | 幀尾 |
|---|---|---|
| 5A | 一字節(jié)數(shù)值 | 3B |
2過(guò)于簡(jiǎn)單的通信協(xié)議引發(fā)的問(wèn)題
3通信協(xié)議常見(jiàn)內(nèi)容
4通信協(xié)議代碼實(shí)現(xiàn)
/* DGUS寄存器地址 *///往DGDS屏指定寄存器寫一字節(jié)數(shù)據(jù)void DGUS_REG_WriteWord(uint8_t RegAddr, uint16_t Data){DGUS_SendByte(DGUS_FRAME_HEAD1);DGUS_SendByte(DGUS_FRAME_HEAD2);DGUS_SendByte(0x04);DGUS_SendByte(DGUS_CMD_W_REG); //指令DGUS_SendByte(RegAddr); //地址DGUS_SendByte((uint8_t)(Data>>8)); //數(shù)據(jù)DGUS_SendByte((uint8_t)(Data&0xFF));}//往DGDS屏指定地址寫一字節(jié)數(shù)據(jù)void DGUS_DATA_WriteWord(uint16_t DataAddr, uint16_t Data){DGUS_SendByte(DGUS_FRAME_HEAD1);DGUS_SendByte(DGUS_FRAME_HEAD2);DGUS_SendByte(0x05);DGUS_SendByte(DGUS_CMD_W_DATA); //指令DGUS_SendByte((uint8_t)(DataAddr>>8)); //地址DGUS_SendByte((uint8_t)(DataAddr&0xFF));DGUS_SendByte((uint8_t)(Data>>8)); //數(shù)據(jù)DGUS_SendByte((uint8_t)(Data&0xFF));}
static uint8_t sDGUS_SendBuf[DGUS_PACKAGE_LEN];//往DGDS屏指定寄存器寫一字節(jié)數(shù)據(jù)void DGUS_REG_WriteWord(uint8_t RegAddr, uint16_t Data){sDGUS_SendBuf[0] = DGUS_FRAME_HEAD1; //幀頭sDGUS_SendBuf[1] = DGUS_FRAME_HEAD2;sDGUS_SendBuf[2] = 0x06; //長(zhǎng)度sDGUS_SendBuf[3] = DGUS_CMD_W_CTRL; //指令sDGUS_SendBuf[4] = RegAddr; //地址sDGUS_SendBuf[5] = (uint8_t)(Data>>8); //數(shù)據(jù)sDGUS_SendBuf[6] = (uint8_t)(Data&0xFF);DGUS_CRC16(&sDGUS_SendBuf[3], sDGUS_SendBuf[2] - 2, &sDGUS_CRC_H, &sDGUS_CRC_L);sDGUS_SendBuf[7] = sDGUS_CRC_H; //校驗(yàn)sDGUS_SendBuf[8] = sDGUS_CRC_L;DGUSSend_Packet_ToQueue(sDGUS_SendBuf, sDGUS_SendBuf[2] + 3);}//往DGDS屏指定地址寫一字節(jié)數(shù)據(jù)void DGUS_DATA_WriteWord(uint16_t DataAddr, uint16_t Data){sDGUS_SendBuf[0] = DGUS_FRAME_HEAD1; //幀頭sDGUS_SendBuf[1] = DGUS_FRAME_HEAD2;sDGUS_SendBuf[2] = 0x07; //長(zhǎng)度sDGUS_SendBuf[3] = DGUS_CMD_W_DATA; //指令sDGUS_SendBuf[4] = (uint8_t)(DataAddr>>8); //地址sDGUS_SendBuf[5] = (uint8_t)(DataAddr&0xFF);sDGUS_SendBuf[6] = (uint8_t)(Data>>8); //數(shù)據(jù)sDGUS_SendBuf[7] = (uint8_t)(Data&0xFF);DGUS_CRC16(&sDGUS_SendBuf[3], sDGUS_SendBuf[2] - 2, &sDGUS_CRC_H, &sDGUS_CRC_L);sDGUS_SendBuf[8] = sDGUS_CRC_H; //校驗(yàn)sDGUS_SendBuf[9] = sDGUS_CRC_L;DGUSSend_Packet_ToQueue(sDGUS_SendBuf, sDGUS_SendBuf[2] + 3);}
typedef struct{uint8_t Head1; //幀頭1uint8_t Head2; //幀頭2uint8_t Len; //長(zhǎng)度uint8_t Cmd; //命令uint8_t Data[DGUS_DATA_LEN]; //數(shù)據(jù)uint16_t CRC16; //CRC校驗(yàn)}DGUS_PACKAGE_TypeDef;
void DGUS_ISRHandler(uint8_t Data){static uint8_t sDgus_RxNum = 0; //數(shù)量static uint8_t sDgus_RxBuf[DGUS_PACKAGE_LEN];static portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;sDgus_RxBuf[gDGUS_RxCnt] = Data;gDGUS_RxCnt++;/* 判斷幀頭 */if(sDgus_RxBuf[0] != DGUS_FRAME_HEAD1) //接收到幀頭1{gDGUS_RxCnt = 0;return;}if((2 == gDGUS_RxCnt) && (sDgus_RxBuf[1] != DGUS_FRAME_HEAD2)){gDGUS_RxCnt = 0;return;}/* 確定一幀數(shù)據(jù)長(zhǎng)度 */if(gDGUS_RxCnt == 3){sDgus_RxNum = sDgus_RxBuf[2] + 3;}/* 接收完一幀數(shù)據(jù) */if((6 <= gDGUS_RxCnt) && (sDgus_RxNum <= gDGUS_RxCnt)){gDGUS_RxCnt = 0;if(xDGUSRcvQueue != NULL) //解析成功, 加入隊(duì)列{xQueueSendFromISR(xDGUSRcvQueue, &sDgus_RxBuf[0], &xHigherPriorityTaskWoken);portEND_SWITCHING_ISR(xHigherPriorityTaskWoken);}}}
b.增加超時(shí)檢測(cè)
接收數(shù)據(jù)有可能存在接收了一半，中斷因?yàn)槟撤N原因中斷了，這時(shí)候，超時(shí)檢測(cè)也很有必要。
比如：用多余的MCU定時(shí)器做一個(gè)超時(shí)計(jì)數(shù)的處理，接收到一個(gè)數(shù)據(jù)，開(kāi)始計(jì)時(shí)，超過(guò)1ms沒(méi)有接收到下一個(gè)數(shù)據(jù)，就丟掉這一包（前面接收的）數(shù)據(jù)。
static void DGUS_TimingAndUpdate(uint16_t Nms){sDGUSTiming_Nms_Num = Nms;TIM_SetCounter(DGUS_TIM, 0); //設(shè)置計(jì)數(shù)值為0TIM_Cmd(DGUS_TIM, ENABLE); //啟動(dòng)定時(shí)器}void DGUS_COM_IRQHandler(void){if((DGUS_COM->SR & USART_FLAG_RXNE) == USART_FLAG_RXNE){DGUS_TimingAndUpdate(5); //更新定時(shí)(防止超時(shí))DGUS_ISRHandler((uint8_t)USART_ReceiveData(DGUS_COM));}}
c.更多
接收和發(fā)送一樣，實(shí)現(xiàn)方法有很多種，比如接收同樣也可以用結(jié)構(gòu)體方式。但有一點(diǎn)，都需要結(jié)合你實(shí)際需求來(lái)編碼。
5最后
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