一、发送HEX数据包

1.1固定包长，含包头包尾（包尾不是必须的）

1.2可变包长，含包头包尾

1、包头包尾和数据载荷重复的问题，传输的数据本身是FF和FE,可能引起误判
解决：限制载荷数据的范围，限幅（例如只发送0~100）
如果无法避免数据于包头包尾重复，则尽量使用固定长度的数据包
增加包头包尾的数量，尽量是其呈现出载荷数据出现不了的状态
2、包头包尾并不是全部都需要的，例如可以只要一个包头
3、固定包长和可变包长的选择问题
（1）对HEX来说，若载荷出现和包头包尾重复的情况，最好选择固定包长，避免接受错误
（2）若不重复，可以选择可变包长
4、各种数据转化为数据流的问题
数据包都是一个字节一个字节组成的，若想发送16位整型数据、32位整型数据，float、double、甚至是结构体（其内部都是由一个字节一个字节组成的），只需要用一个uint8_t的指针指向它，把数据当作字节数组发送即可

二、接收HEX数据包

每收到一个字节，函数都会进入一次中断，在中断函数中，可以拿到一个字节，但拿到字节之后，就得退出中断，故每拿到一个数据，都是一个独立的过程，而对数据包来说，有数据、包头、包尾三种状态，根据状态不同处理也不同。

三、发送文本数据包

3.1固定包长，含包头包尾

3.2可变包长，含包头包尾

四、接收文本数据包

五、HEX数据包和文本数据包的比较

（1）在hex数据包中，数据都是以原始的字节数据本身呈现的

（2）在文本数据包中，每个字节就经过一层编码和译码，最终表现出文本格式（文本背后还是一个字节的HEX数据）

（3）hex数据包：传输直接、解析数据简单，适合一些模块发送原始的数据，比如一些使用串口通信的陀螺仪、温湿度传感器，但是灵活性不足、载荷容易和包头包尾重复

（4）文本数据包：数据直观易理解、灵活，适合一些输入指令进行人机交互，但解析效率低.

（5）发送100，hex直接发送一个字节100，而文本发送三个字节’1’,‘0’.‘0’，收到之后还要把字符转换程数据，才能得到100。

六、程序用例

6.1串口收发HEX数据包

6.1.1接线图

6.1.2程序代码

Serial.c

#include "stm32f10x.h"                  // Device header
#include <stdio.h>
#include <stdarg.h>uint8_t Serial_TxPacket[4];				//FF 01 02 03 04 FE
uint8_t Serial_RxPacket[4];
uint8_t Serial_RxFlag;void Serial_Init(void)
{RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);GPIO_InitTypeDef GPIO_InitStructure;GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;GPIO_Init(GPIOA, &GPIO_InitStructure);GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;GPIO_Init(GPIOA, &GPIO_InitStructure);USART_InitTypeDef USART_InitStructure;USART_InitStructure.USART_BaudRate = 9600;USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;USART_InitStructure.USART_Mode = USART_Mode_Tx | USART_Mode_Rx;USART_InitStructure.USART_Parity = USART_Parity_No;USART_InitStructure.USART_StopBits = USART_StopBits_1;USART_InitStructure.USART_WordLength = USART_WordLength_8b;USART_Init(USART1, &USART_InitStructure);USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);NVIC_InitTypeDef NVIC_InitStructure;NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;NVIC_Init(&NVIC_InitStructure);USART_Cmd(USART1, ENABLE);
}void Serial_SendByte(uint8_t Byte)
{USART_SendData(USART1, Byte);while (USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET);
}void Serial_SendArray(uint8_t *Array, uint16_t Length)
{uint16_t i;for (i = 0; i < Length; i ++){Serial_SendByte(Array[i]);}
}void Serial_SendString(char *String)
{uint8_t i;for (i = 0; String[i] != '\\0'; i ++){Serial_SendByte(String[i]);}
}uint32_t Serial_Pow(uint32_t X, uint32_t Y)
{uint32_t Result = 1;while (Y --){Result *= X;}return Result;
}void Serial_SendNumber(uint32_t Number, uint8_t Length)
{uint8_t i;for (i = 0; i < Length; i ++){Serial_SendByte(Number / Serial_Pow(10, Length - i - 1) % 10 + '0');}
}int fputc(int ch, FILE *f)
{Serial_SendByte(ch);return ch;
}void Serial_Printf(char *format, ...)
{char String[100];va_list arg;va_start(arg, format);vsprintf(String, format, arg);va_end(arg);Serial_SendString(String);
}void Serial_SendPacket(void)
{Serial_SendByte(0xFF);Serial_SendArray(Serial_TxPacket, 4);Serial_SendByte(0xFE);
}uint8_t Serial_GetRxFlag(void)
{if (Serial_RxFlag == 1){Serial_RxFlag = 0;return 1;}return 0;
}void USART1_IRQHandler(void)
{static uint8_t RxState = 0;static uint8_t pRxPacket = 0;if (USART_GetITStatus(USART1, USART_IT_RXNE) == SET){uint8_t RxData = USART_ReceiveData(USART1);if (RxState == 0){if (RxData == 0xFF){RxState = 1;pRxPacket = 0;}}else if (RxState == 1){Serial_RxPacket[pRxPacket] = RxData;pRxPacket ++;if (pRxPacket >= 4){RxState = 2;}}else if (RxState == 2){if (RxData == 0xFE){RxState = 0;Serial_RxFlag = 1;}}USART_ClearITPendingBit(USART1, USART_IT_RXNE);}
}

main.c

#include "stm32f10x.h"                  // Device header
#include "Delay.h"
#include "OLED.h"
#include "Serial.h"
#include "Key.h"uint8_t KeyNum;int main(void)
{OLED_Init();Key_Init();Serial_Init();OLED_ShowString(1, 1, "TxPacket");OLED_ShowString(3, 1, "RxPacket");Serial_TxPacket[0] = 0x01;Serial_TxPacket[1] = 0x02;Serial_TxPacket[2] = 0x03;Serial_TxPacket[3] = 0x04;while (1){KeyNum = Key_GetNum();if (KeyNum == 1){Serial_TxPacket[0] ++;Serial_TxPacket[1] ++;Serial_TxPacket[2] ++;Serial_TxPacket[3] ++;Serial_SendPacket();OLED_ShowHexNum(2, 1, Serial_TxPacket[0], 2);OLED_ShowHexNum(2, 4, Serial_TxPacket[1], 2);OLED_ShowHexNum(2, 7, Serial_TxPacket[2], 2);OLED_ShowHexNum(2, 10, Serial_TxPacket[3], 2);}if (Serial_GetRxFlag() == 1){OLED_ShowHexNum(4, 1, Serial_RxPacket[0], 2);OLED_ShowHexNum(4, 4, Serial_RxPacket[1], 2);OLED_ShowHexNum(4, 7, Serial_RxPacket[2], 2);OLED_ShowHexNum(4, 10, Serial_RxPacket[3], 2);}}
}

6.2串口收发文本数据包

6.21.1接线图

6.2.2程序代码

Serial.c

#include "stm32f10x.h"                  // Device header
#include <stdio.h>
#include <stdarg.h>char Serial_RxPacket[100];				//"@MSG\\r\\n"
uint8_t Serial_RxFlag;void Serial_Init(void)
{RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);GPIO_InitTypeDef GPIO_InitStructure;GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;GPIO_Init(GPIOA, &GPIO_InitStructure);GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;GPIO_Init(GPIOA, &GPIO_InitStructure);USART_InitTypeDef USART_InitStructure;USART_InitStructure.USART_BaudRate = 9600;USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;USART_InitStructure.USART_Mode = USART_Mode_Tx | USART_Mode_Rx;USART_InitStructure.USART_Parity = USART_Parity_No;USART_InitStructure.USART_StopBits = USART_StopBits_1;USART_InitStructure.USART_WordLength = USART_WordLength_8b;USART_Init(USART1, &USART_InitStructure);USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);NVIC_InitTypeDef NVIC_InitStructure;NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;NVIC_Init(&NVIC_InitStructure);USART_Cmd(USART1, ENABLE);
}void Serial_SendByte(uint8_t Byte)
{USART_SendData(USART1, Byte);while (USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET);
}void Serial_SendArray(uint8_t *Array, uint16_t Length)
{uint16_t i;for (i = 0; i < Length; i ++){Serial_SendByte(Array[i]);}
}void Serial_SendString(char *String)
{uint8_t i;for (i = 0; String[i] != '\\0'; i ++){Serial_SendByte(String[i]);}
}uint32_t Serial_Pow(uint32_t X, uint32_t Y)
{uint32_t Result = 1;while (Y --){Result *= X;}return Result;
}void Serial_SendNumber(uint32_t Number, uint8_t Length)
{uint8_t i;for (i = 0; i < Length; i ++){Serial_SendByte(Number / Serial_Pow(10, Length - i - 1) % 10 + '0');}
}int fputc(int ch, FILE *f)
{Serial_SendByte(ch);return ch;
}void Serial_Printf(char *format, ...)
{char String[100];va_list arg;va_start(arg, format);vsprintf(String, format, arg);va_end(arg);Serial_SendString(String);
}void USART1_IRQHandler(void)
{static uint8_t RxState = 0;static uint8_t pRxPacket = 0;if (USART_GetITStatus(USART1, USART_IT_RXNE) == SET){uint8_t RxData = USART_ReceiveData(USART1);if (RxState == 0){if (RxData == '@' && Serial_RxFlag == 0){RxState = 1;pRxPacket = 0;}}else if (RxState == 1){if (RxData == '\\r'){RxState = 2;}else{Serial_RxPacket[pRxPacket] = RxData;pRxPacket ++;}}else if (RxState == 2){if (RxData == '\\n'){RxState = 0;Serial_RxPacket[pRxPacket] = '\\0';Serial_RxFlag = 1;}}USART_ClearITPendingBit(USART1, USART_IT_RXNE);}
}

main.c

#include "stm32f10x.h"                  // Device header
#include "Delay.h"
#include "OLED.h"
#include "Serial.h"
#include "LED.h"
#include "string.h"int main(void)
{OLED_Init();LED_Init();Serial_Init();OLED_ShowString(1, 1, "TxPacket");OLED_ShowString(3, 1, "RxPacket");while (1){if (Serial_RxFlag == 1){OLED_ShowString(4, 1, "                ");OLED_ShowString(4, 1, Serial_RxPacket);if (strcmp(Serial_RxPacket, "LED_ON") == 0){LED1_ON();Serial_SendString("LED_ON_OK\\r\\n");OLED_ShowString(2, 1, "                ");OLED_ShowString(2, 1, "LED_ON_OK");}else if (strcmp(Serial_RxPacket, "LED_OFF") == 0){LED1_OFF();Serial_SendString("LED_OFF_OK\\r\\n");OLED_ShowString(2, 1, "                ");OLED_ShowString(2, 1, "LED_OFF_OK");}else{Serial_SendString("ERROR_COMMAND\\r\\n");OLED_ShowString(2, 1, "                ");OLED_ShowString(2, 1, "ERROR_COMMAND");}Serial_RxFlag = 0;}}
}