一种用于嵌入式通信传输和存储设备的C语言实现方法

摘要：各种类型的数据传输和存储就涉及到大小端的问题，首先要简单说下芯片的大小端问题，这里主要讨论Cortex-M内核。

M内核支持大端或者小端，实际应用中大部分内核都是小端。以STM32为例，全部都是小端，而且是芯片设计之初就固化进去的，不可修改。市面上其他厂家基本也都固化的小端格式。

F1编程手册

F3和F4编程手册

F7和H7编程手册

各种数据类型编程EEPROM，SPI Flash等存储器的简易方法，一般这些存储器都是字节编程，写入浮点等数据类型时不太方便。这里分享一个方法，定义一个结构体，将各种数据类型封装进去：

写入的时候采用下面方式：

读取时可以采用下面方式：

各种数据类型的SPI，UART，I2C等传输问题。这里我们以串口通信为例，比如主机要发送如下格式数据给从机：

我们可以做一个如下结构体格式：

 

typedef struct
{
    uint8_t ucStart;                        

    uint16_t usCO2;
    uint16_t usPM25;        
    uint16_t usHumidity;          
    float    Temprature;
    uint32_t ulParam;
    uint8_t  ucEnd1;           
    uint8_t  ucEnd2;   
}
UART_T;

UART_T g_tUartParam;

 

主机发送的时候我们就可以采用如下方法:

 

comSendBuf(COM1, (uint8_t *)&g_tUartParam, sizeof(UART_T));

 

从机工程也定义一个同样的结构体变量，比如我们把接收到一帧数据存到缓冲uint8_t buf[50]里面了。

我们就可以定义一个结构体指针变量：

 

UART_T *pUartParam;
pUartParam = (UART_T *)buf;

 

那么我们就可以pUartParam->usCO2,pUartParam->Temprature等方式来访问，非常方便。

代码实现

结构体数据如下：

 

typedef struct
{
    uint8_t ucStart;                        
 
    uint16_t usCO2;
    uint16_t usPM25;        
    uint16_t usHumidity;         
    float    Temprature;
    uint32_t ulParam;
    uint8_t  ucEnd1;           
    uint8_t  ucEnd2;   
}
USART_T;
 
USART_T g_tUartParam; /* 串口1发送数据使用 */
USART_T *pUartParam;  /* 串口2接数据使用 */
uint8_t buf[128];     /* 接收记录缓冲 */

 

数据收发处理：

 

/*
*********************************************************************************************************
*        函 数 名: main
*        功能说明: c程序入口
*        形    参: 无
*        返 回 值: 错误代码(无需处理)
*********************************************************************************************************
*/
int main(void)
{
        uint8_t ucKeyCode;        
        uint8_t read;
        uint8_t ucStatus = 0;  /* 状态机标志 */
        uint8_t ucCount=0;
        float ftest = 0.11f;
        pUartParam = (USART_T *)buf;
         
         
        bsp_Init();                /* 硬件初始化 */
         
        PrintfLogo();        /* 打印例程名称和版本等信息 */
        PrintfHelp();        /* 打印操作提示 */
 
 
        bsp_StartAutoTimer(0, 100); /* 启动1个100ms的自动重装的定时器 */
         
        memset(buf, 0, 128);
         
        /* 进入主程序循环体 */
        while (1)
        {
                bsp_Idle();                /* 这个函数在bsp.c文件。用户可以修改这个函数实现CPU休眠和喂狗 */
 
                /* 判断定时器超时时间 */
                if (bsp_CheckTimer(0))        
                {
                        /* 每隔100ms 进来一次 */ 
                        bsp_LedToggle(2);                        
                }
                 
                /* 按键滤波和检测由后台systick中断服务程序实现，我们只需要调用bsp_GetKey读取键值即可。 */
                ucKeyCode = bsp_GetKey();        /* 读取键值, 无键按下时返回 KEY_NONE = 0 */
                if (ucKeyCode != KEY_NONE)
                {
                        switch (ucKeyCode)
                        {
                                case KEY_DOWN_K1:                        /* K1键按下，串口1发送数据给串口2 */
                                        g_tUartParam.ucStart = '$';
                                        g_tUartParam.usCO2 = 1;
                                        g_tUartParam.usPM25 = 2;
                                        g_tUartParam.usHumidity = 3;
                                        g_tUartParam.Temprature = ftest++;
                                        g_tUartParam.ulParam = 5;        
                                        g_tUartParam.ucEnd1 = '
';        
                                        g_tUartParam.ucEnd2 = '
';
                                        comSendBuf(COM1, (uint8_t *)&g_tUartParam, sizeof(UART_T));
                                        printf("发送数据完成
");
                                        break;
 
                                default:
                                        /* 其它的键值不处理 */
                                        break;
                        }
                }
                 
                /* 串口2接收数据解析处理 */
                if (comGetChar(COM2, &read))
                {
                        switch (ucStatus)
                        {
                                /* 状态0保证接收到0x01 */
                                case 0:
                                        if(read == '$')
                                        {
                                                ucStatus = 1; 
                                                buf[ucCount++] = read;
                                        }
                                        break;
 
                                case 1:
                                        buf[ucCount] = read;
                                    
                                        /* 接收够15个数据 */
                                        if((buf[ucCount-1] == '
')&&(buf[ucCount] == '
'))
                                        {
                                                /* 打印接收到的数据值 */
                                                printf("接收到的数据：
");
                                                printf("pUartParam->usCO2 = %d
", pUartParam->usCO2);
                                                printf("pUartParam->usPM25 = %d
", pUartParam->usPM25);
                                                printf("pUartParam->usHumidity = %d
", pUartParam->usHumidity);
                                                printf("pUartParam->Temprature = %f
", pUartParam->Temprature);
                                                printf("pUartParam->ulParam = %d
", pUartParam->ulParam);                                                
                                                printf("
");
                                                 
                                                memset(buf, 0, 128);
                                                ucStatus = 0;
                                                ucCount=0;
                                        }
                                        else
                                        {
                                                ucCount++;
                                        }
                                        break;
                                 
                                default:
                                        break;
                        }
                }
        }
}

 

测试效果

 
 

　　审核编辑：汤梓红