直接使用官方給出的例子，具體參考 https://www.rt-thread.org/document/site/programming-manual/device/uart/uart/
/*
* 程序清單：這是一個串口設備 DMA 接收使用例程
* 例程導出了 uart_dma_sample 命令到控制終端
* 命令調用格式：uart_dma_sample uart3
* 命令解釋：命令第二個參數是要使用的串口設備名稱，爲空則使用默認的串口設備
* 程序功能：通過串口輸出字符串"hello RT-Thread!"，並通過串口輸出接收到的數據，然後打印接收到的數據。
*/
#include <rtthread.h>
#define SAMPLE_UART_NAME "uart3" /* 串口設備名稱 */
/* 串口接收消息結構*/
struct rx_msg
{
rt_device_t dev;
rt_size_t size;
};
/* 串口設備句柄 */
static rt_device_t serial;
/* 消息隊列控制塊 */
static struct rt_messagequeue rx_mq;
/* 接收數據回調函數 */
static rt_err_t uart_input(rt_device_t dev, rt_size_t size)
{
struct rx_msg msg;
rt_err_t result;
msg.dev = dev;
msg.size = size;
result = rt_mq_send(&rx_mq, &msg, sizeof(msg));
if ( result == -RT_EFULL)
{
/* 消息隊列滿 */
rt_kprintf("message queue full！\n");
}
return result;
}
static void serial_thread_entry(void *parameter)
{
struct rx_msg msg;
rt_err_t result;
rt_uint32_t rx_length;
static char rx_buffer[RT_SERIAL_RB_BUFSZ + 1];
while (1)
{
rt_memset(&msg, 0, sizeof(msg));
/* 從消息隊列中讀取消息*/
result = rt_mq_recv(&rx_mq, &msg, sizeof(msg), RT_WAITING_FOREVER);
if (result == RT_EOK)
{
/* 從串口讀取數據*/
rx_length = rt_device_read(msg.dev, 0, rx_buffer, msg.size);
rx_buffer[rx_length] = '\0';
/* 通過串口設備 serial 輸出讀取到的消息 */
rt_device_write(serial, 0, rx_buffer, rx_length);
/* 打印數據 */
rt_kprintf("%s\n",rx_buffer);
}
}
}
static int uart_dma_sample(int argc, char *argv[])
{
rt_err_t ret = RT_EOK;
char uart_name[RT_NAME_MAX];
static char msg_pool[256];
char str[] = "hello RT-Thread!\r\n";
if (argc == 2)
{
rt_strncpy(uart_name, argv[1], RT_NAME_MAX);
}
else
{
rt_strncpy(uart_name, SAMPLE_UART_NAME, RT_NAME_MAX);
}
/* 查找串口設備 */
serial = rt_device_find(uart_name);
if (!serial)
{
rt_kprintf("find %s failed!\n", uart_name);
return RT_ERROR;
}
/* 初始化消息隊列 */
rt_mq_init(&rx_mq, "rx_mq",
msg_pool, /* 存放消息的緩衝區 */
sizeof(struct rx_msg), /* 一條消息的最大長度 */
sizeof(msg_pool), /* 存放消息的緩衝區大小 */
RT_IPC_FLAG_FIFO); /* 如果有多個線程等待，按照先來先得到的方法分配消息 */
/* 以 DMA 接收及輪詢發送方式打開串口設備 */
rt_device_open(serial, RT_DEVICE_FLAG_DMA_RX);
/* 設置接收回調函數 */
rt_device_set_rx_indicate(serial, uart_input);
/* 發送字符串 */
rt_device_write(serial, 0, str, (sizeof(str) - 1));
/* 創建 serial 線程 */
rt_thread_t thread = rt_thread_create("serial", serial_thread_entry, RT_NULL, 1024, 25, 10);
/* 創建成功則啓動線程 */
if (thread != RT_NULL)
{
rt_thread_startup(thread);
}
else
{
ret = RT_ERROR;
}
return ret;
}
/* 導出到 msh 命令列表中 */
MSH_CMD_EXPORT(uart_dma_sample, uart device dma sample);
串口調試助手查看串口數據輸出，發現了分包問題。
目前的解決方法是:
第一步: 將這個HAL庫函數裏面的內容屏蔽
/**
* @brief Rx Transfer completed callback
* @param huart: UART handle
* @note This example shows a simple way to report end of DMA Rx transfer, and
* you can add your own implementation.
* @retval None
*/
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
// struct rt_serial_device *serial;
// struct stm32_uart *uart;
// rt_size_t recv_len;
// rt_base_t level;
// RT_ASSERT(huart != NULL);
// uart = (struct stm32_uart *)huart;
// serial = &uart->serial;
// level = rt_hw_interrupt_disable();
// recv_len = serial->config.bufsz - uart->dma.last_index;
// uart->dma.last_index = 0;
// rt_hw_interrupt_enable(level);
// if (recv_len)
// {
// rt_hw_serial_isr(serial, RT_SERIAL_EVENT_RX_DMADONE | (recv_len << 8));
// }
}
第二步.根據你接收字符串的最大長度，設置合適的RT_SERIAL_RB_BUFSZ參數
#define RT_SERIAL_RB_BUFSZ 256
2020.1.29更新部分
更新了HAL庫後，需要進行屏蔽如下代碼中屏蔽的內容：
/**
* @brief Rx Transfer completed callback
* @param huart: UART handle
* @note This example shows a simple way to report end of DMA Rx transfer, and
* you can add your own implementation.
* @retval None
*/
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
struct stm32_uart *uart;
RT_ASSERT(huart != NULL);
uart = (struct stm32_uart *)huart;
// dma_isr(&uart->serial);
}
/**
* @brief Rx Half transfer completed callback
* @param huart: UART handle
* @note This example shows a simple way to report end of DMA Rx Half transfer,
* and you can add your own implementation.
* @retval None
*/
void HAL_UART_RxHalfCpltCallback(UART_HandleTypeDef *huart)
{
struct stm32_uart *uart;
RT_ASSERT(huart != NULL);
uart = (struct stm32_uart *)huart;
// dma_isr(&uart->serial);
}
更多詳細的討論請參考