串口驱动学习

0.串口驱动的使用方法

//定义一个时间
struct rt_event system_event;
#define SYS_EVENT_UART_RX_FINISH    0x00000001 /* UART receive data finish event */

/*串口接收回调函数 Receive data callback function */
static rt_err_t uart_input(rt_device_t dev, rt_size_t size)
{
    //有数据到来，通知读取数据
    rt_event_send(&system_event, SYS_EVENT_UART_RX_FINISH);
    return RT_EOK;
}

static void test1_thread_entry(void* parameter)
{
    rt_device_t uart_dev;
    uint8_t data[30] = {0};
    uint8_t data1[30] = {0};
    uint16_t i = 0;
    uint16_t data_length = 0;
    rt_uint32_t sys_event_recv = 0;
    rt_err_t result = rt_event_init(&system_event, "event", RT_IPC_FLAG_FIFO);
    //查找设备
    uart_dev = rt_device_find("usart3");
    //打开设备
    rt_device_open(uart_dev, RT_DEVICE_FLAG_INT_RX);//打开接收
    /* 注册一个数据接收回调函数*/
    rt_device_set_rx_indicate(uart_dev, uart_input);
    
    for(i=0;i<sizeof(data);i++)
    {
        data[i]=i+1;
    }
    if(RT_EOK == rt_device_open(uart_dev, RT_DEVICE_FLAG_INT_RX))//打开中断
    {
        //串口发送数据
       rt_device_write(uart_dev, RT_NULL, data, sizeof(data)); 
    }
    while(1)
    {
        rt_thread_delay(50);
        /* 等待数据到来事件 */
        if(RT_EOK == rt_event_recv(&system_event, SYS_EVENT_UART_RX_FINISH, RT_EVENT_FLAG_OR | RT_EVENT_FLAG_CLEAR, 10, &sys_event_recv))
        {
            
            data_length = rt_device_read(uart_dev, RT_NULL, data1, RT_SERIAL_RB_BUFSZ);
            rt_device_write(uart_dev, RT_NULL, data1, data_length); 
        }   
    }
}

串口驱动抽象层

1.串口配置

struct serial_configure
{
    rt_uint32_t baud_rate;

    rt_uint32_t data_bits               :4;
    rt_uint32_t stop_bits               :2;
    rt_uint32_t parity                  :2;
    rt_uint32_t hardwareflow_control    :2;
    rt_uint32_t mode                    :2;
    rt_uint32_t bufsz                   :16;
    rt_uint32_t reserved                :6;
};

2.串口抽象操作

/**
 * uart operators
 */
struct rt_uart_ops
{	
    //配置函数
    rt_err_t (*configure)(struct rt_serial_device *serial, struct serial_configure *cfg);
    //控制函数
    rt_err_t (*control)(struct rt_serial_device *serial, int cmd, void *arg);
	//发送一个字符
    int (*putc)(struct rt_serial_device *serial, char c);
    //接收一个字符
    int (*getc)(struct rt_serial_device *serial);
	//dma数据发送
    rt_size_t (*dma_transmit)(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction);
};

3.串口驱动抽象

    

struct rt_serial_device
{
    struct rt_device          parent;//RTT设备驱动抽象

    const struct rt_uart_ops *ops;//串口抽象层操作函数
    struct serial_configure   config;//串口配置

    void *serial_rx;
    void *serial_tx;
};
typedef struct rt_serial_device rt_serial_t;

串口驱动硬件层

这个结构体封装N32L40x相关的串口硬件参数

struct n32l40x_uart
{
    USART_Module* uart_periph;       // Todo: 3bits串口号
    IRQn_Type irqn;                  // Todo: 7bits 串口中断号  
    uint32_t per_clk;                // Todo: 5bits串口时钟
    uint32_t tx_gpio_clk;            // Todo: 5bits发送引脚时钟
    uint32_t rx_gpio_clk;            // Todo: 5bits接收引脚时钟
    GPIO_Module* tx_port;            // Todo: 4bits发送引脚分gpio分组
    uint32_t tx_af;                  // Todo: 4bits发送引脚的复用
    uint16_t tx_pin;                 // Todo: 4bits发送引脚pin
    GPIO_Module* rx_port;            // Todo: 4bits接收引脚分gpio分组
    uint32_t rx_af;                  // Todo: 4bits接收引脚的复用
    uint16_t rx_pin;                 // Todo: 4bits接收引脚pin

    struct rt_serial_device * serial;    	//串口驱动抽象父类
    char *device_name;						//串口名字
};

分析已经有的串口设备驱动程序

定义一个串口配置函数
定义一个串口控制函数
定义一个串口的单字符发送函数
定义一个串口的单字符接收函数
定义一个统一的串口中断处理函数
在同一的串口处理函数内部，清楚中断标志后，调用父类的中断处理函数 rt_hw_serial_isr
定义一个struct rt_uart_ops 对象分别赋值内部的，configure，control，putc，getc，dma_transmit（dma发送非必须）
注册串口设备对象 rt_hw_serial_register