[经验]

【RA4M2-SENSOR】—— 13.串口实现循环队列

jf_43382582

2025-9-1 11:46:23

862 RA4M2设计挑战赛

循环队列

上节我已经讲解并实现了使用串口实现不定长度数据的接收，本篇帖子我来采用环形队列来实现不定长度数据的接收和发送。

循环队列在嵌入式当中应用的十分广泛，很多协议的解析都需要环形队列来进行数据的收发。

好了，话不多说，直接进入正题。

我的核心代码如下：
#ifndef USART_RING_H_
#define USART_RING_H_

#include "hal_data.h"

#define UART_RX_BUFFER_SIZE 128

uint16_t uart_available(void);
uint8_t uart_read(void);
void clear_uart_buff();

#endif /* USART_RING_H_ */

#include "usart_ring.h"

/////////////////// USART /////////////////////
volatile uint16_t rx_buffer_head = 0;
volatile uint16_t rx_buffer_tail = 0;
uint8_t rx_buffer[UART_RX_BUFFER_SIZE] = {0,};

void clear_uart_buff()
{
rx_buffer_head = 0;
rx_buffer_tail = 0;
}

uint16_t uart_available(void)
{
return ((uint16_t)(UART_RX_BUFFER_SIZE + rx_buffer_head - rx_buffer_tail)) % UART_RX_BUFFER_SIZE;
}

uint8_t uart_read(void)
{
if(rx_buffer_head == rx_buffer_tail)
{
return 0;
}
else
{
uint8_t c = rx_buffer[rx_buffer_tail];
rx_buffer_tail = (uint16_t)(rx_buffer_tail + 1) % UART_RX_BUFFER_SIZE;
return c;
}
}

上面就是循环队列的功能函数

主要是要在串口中断接收函数中进行调用处理

void uart9_callback (uart_callback_args_t * p_args)
{
if(p_args->event == UART_EVENT_TX_COMPLETE)
{
uart_send_complete_flag = true;
}
if(p_args->event == UART_EVENT_RX_CHAR)
{

//if(U1_Rxlen >= sizeof(U1_RxBuff))	U1_Rxlen = 0; //防止串口被刷爆
	//U1_RxBuff[U1_Rxlen++] = (uint8_t)p_args->data;


	uint8_t rbyte = (uint8_t)p_args->data;
	uint16_t i = (uint16_t)(rx_buffer_head + 1) % UART_RX_BUFFER_SIZE;
	
	if(i != rx_buffer_tail)
	{
		rx_buffer[rx_buffer_head] = rbyte;
		rx_buffer_head = i;
	}

	
}

}
主函数中添加核心代码

将串口接收到的不定长度的数据发送回去

#include "hal_data.h"
#include "usart9.h"
#include "Systick.h"
#include "string.h"
#include "stdio.h"

#include "usart_ring.h"

FSP_CPP_HEADER
void R_BSP_WarmStart(bsp_warm_start_event_t event);
FSP_CPP_FOOTER

/*******************************************************************************************************************//**

main() is generated by the RA Configuration editor and is used to generate threads if an RTOS is used. This function
is called by main() when no RTOS is used.
*********************************************************************************************************************/
void hal_entry(void)
{
/ TODO: add your own code here */
hal_systick_init();

UART9_Init();
#define SIZE_BF 32

while(1)
{
if(uart_available())
{
char str[SIZE_BF] = {0,};
uint8_t i = 0;
```
while(uart_available())
 	{
 		str[i++] = uart_read(); 

 		if(i == SIZE_BF - 1)
 		{
 			str[i] = '\0';
 			break;
 		}

 		//HAL_Delay(1);
 	}

 	str[i] = '\0';

 	uart9_Send_Bytes((uint8_t*)str, strlen(str));
 }
```
}

#if BSP_TZ_SECURE_BUILD
/* Enter non-secure code */
R_BSP_NonSecureEnter();
#endif
}

/*******************************************************************************************************************//**

This function is called at various points during the startup process. This implementation uses the event that is
called right before main() to set up the pins.
@param[in] event Where at in the start up process the code is currently at
**********************************************************************************************************************/
void R_BSP_WarmStart (bsp_warm_start_event_t event)
{
if (BSP_WARM_START_RESET == event)
{
#if BSP_FEATURE_FLASH_LP_VERSION != 0
```
/* Enable reading from data flash. */
 R_FACI_LP->DFLCTL = 1U;

 /* Would normally have to wait tDSTOP(6us) for data flash recovery. Placing the enable here, before clock and
  * C runtime initialization, should negate the need for a delay since the initialization will typically take more than 6us. */
```

#endif
}

if (BSP_WARM_START_POST_C == event)
{
    /* C runtime environment and system clocks are setup. */

    /* Configure pins. */
    R_IOPORT_Open(&IOPORT_CFG_CTRL, &IOPORT_CFG_NAME);

#if BSP_CFG_SDRAM_ENABLED

/* Setup SDRAM and initialize it. Must configure pins first. */
    R_BSP_SdramInit(true);

#endif
}
}

#if BSP_TZ_SECURE_BUILD

FSP_CPP_HEADER
BSP_CMSE_NONSECURE_ENTRY void template_nonsecure_callable ();

/* Trustzone Secure Projects require at least one nonsecure callable function in order to build (Remove this if it is not required to build). */
BSP_CMSE_NONSECURE_ENTRY void template_nonsecure_callable ()
{

}
FSP_CPP_FOOTER

#endif