1.定義一個空的指針函數 指針函數的參數是uint8_t 類型ch

typedef void (* usart_recv_callback)(uint8_t ch);

2.聲明這個類型

usart_recv_callback  usart1_recv_cb;

3.串口配置時，一個形參為串口中斷接收回調

void Usart_Config(USART_TypeDef* USARTx, uint32_t baudRate, usart_recv_callback cb)

{

 GPIO_InitTypeDef GPIO_InitStructure;    USART_InitTypeDef USART_InitStructure;    NVIC_InitTypeDef NVIC_InitStructure;    if(USARTx == USART1)    {        usart1_recv_cb = cb;        RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1 | RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);        /* Configure USART1 Tx (PA.09) as alternate function push-pull */        GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;        GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;        GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;        GPIO_Init(GPIOA, &GPIO_InitStructure);        /* Configure USART1 Rx (PA.10) as input floating */        GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;        GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;        GPIO_Init(GPIOA, &GPIO_InitStructure);        USART_InitStructure.USART_BaudRate = baudRate;        USART_InitStructure.USART_WordLength = USART_WordLength_8b;        USART_InitStructure.USART_StopBits = USART_StopBits_1;        USART_InitStructure.USART_Parity = USART_Parity_No;        USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;        USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;        USART_Init(USART1, &USART_InitStructure);        if(cb)        {            USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);            /* Enable the USARTy Interrupt */            NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;            NVIC_InitStructure.NVIC_IRQChannelPReemptionPriority = 0;            NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;            NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;            NVIC_Init(&NVIC_InitStructure);        }        USART_Cmd(USART1, ENABLE);    }

}

分析：usart1_recv_cb = cb;這句語句是將形參指針函數 cb 賦值給 usart1_recv_cb

            if(cb):是判斷回調函數指針是否為空，如果不為空則中斷初始化

4.串口中斷函數

void USART1_IRQHandler(void){     uint8_t ch;     if(USART_GetITStatus(USART1, USART_IT_RXNE) != RESET)     {         /* Read one byte from the receive data register */         ch = USART_ReceiveData(USART1);         usart1_recv_cb(ch);         USART_ClearITPendingBit(USART1, USART_IT_RXNE);     }}

分析：將串口1中斷接收到的值賦值給ch，然后ch作為usart1_recv_cb函數的輸入參數

5.

void HCHO_Test(uint8_t recv_data){if((sensorstr.hcho_addr == 0) && (recv_data != 0xff)){        sensorstr.hcho_addr = 0;return;}if((sensorstr.hcho_addr == 1) && (recv_data != 0x17)){   sensorstr.hcho_addr = 0;return;}if((sensorstr.hcho_addr == 2) && (recv_data != 0x04)){        sensorstr.hcho_addr = 0;return;}    sensorstr.hcho_packet[sensorstr.hcho_addr++] = recv_data;}

分析：void HCHO_Test(uint8_t recv_data)函數就是我們所說的回調函數，此函數和 1.里所定義的void (* usart_recv_callback)(uint8_t ch)函數指針是對應的。

6.

int main(void)

{

Usart_Config(PM_UART, 9600, PM_Test);

}

PM_Test函數首地址就是usart_recv_callback cb的形參