[嵌入式]单片机IO模拟串口程序

有个项目串口不够用，所以打算用IO口模拟一个串口进行通讯。

参考了网上的代码，接收方法大同小异，但是发送大多数人都是用阻塞式的。阻塞式优点是可以节省单片机资源，只需要一个准确的延时函数即可。但是CPU在发送期间不能做其他事情，而使用定时器中断发送可解决这个问题，缺点是需要独占定时器。

代码在GD32303E开发板上运行通过，使用串口助手收发正常。

源文件

#include "bsp_io_uart.h"

//104us  9600 buad
#define UART_IO_DELAY_COUNT  104

static uint8 *pu8RxBuff = NULL;
static uint16 u16RxPos = 0;
static uint16 u16RxCount = 0;
static uint8 u8RevData = 0;
static uint8 u8Pos = 0;

static uint8 *pu8TxBuff = NULL;
static uint16 u16TxPos = 0;
static uint16 u16TxCount = 0;
static uint8 u8SendData = 0;
static uint8 u8SendPos = 0;

static void BspIoUartT3Init(void);
static void BspIoUartT4Init(void);

typedef enum
{
	eStart = 0,
	eTransmit,
	eStop,		
}eBspIoUartTxStep;

static eBspIoUartTxStep eUartStep;

void BspIoUartInit(void)
{
	BspIoUartT3Init();	
	BspIoUartT4Init();
	
	rcu_periph_clock_enable(RCU_AF);	
	rcu_periph_clock_enable(RCU_GPIOB);		
	
	//PB8	RX
	nvic_irq_enable(EXTI5_9_IRQn, 0U, 0U);		
	
	gpio_init(GPIOB, GPIO_MODE_IPU, GPIO_OSPEED_50MHZ, GPIO_PIN_8);							

	gpio_exti_source_select(GPIO_PORT_SOURCE_GPIOB, GPIO_PIN_SOURCE_8);
	exti_init(EXTI_8, EXTI_INTERRUPT, EXTI_TRIG_FALLING);
	exti_interrupt_flag_clear(EXTI_8);	
	
	//PB9	TX	
	gpio_bit_set(GPIOB, GPIO_PIN_9);
	gpio_init(GPIOB, GPIO_MODE_OUT_PP, GPIO_OSPEED_50MHZ, GPIO_PIN_9);	
}         

static void BspIoUartT4Init(void)
{
	timer_parameter_struct timer_initpara;	
	
	nvic_irq_enable(TIMER4_IRQn, 0, 0);		
	rcu_periph_clock_enable(RCU_TIMER4);	
	
	timer_deinit(TIMER4);
	timer_struct_para_init(&timer_initpara);
	
	timer_initpara.prescaler         = 0;
	timer_initpara.alignedmode       = TIMER_COUNTER_EDGE;
	timer_initpara.counterdirection  = TIMER_COUNTER_UP;
	timer_initpara.period            = UART_IO_DELAY_COUNT * 120 - 1;
	timer_initpara.clockdivision     = TIMER_CKDIV_DIV1;
	timer_init(TIMER4, &timer_initpara);

	timer_interrupt_flag_clear(TIMER4, TIMER_INT_FLAG_UP);
	timer_interrupt_enable(TIMER4, TIMER_INT_UP);		
	timer_disable(TIMER4);
}

void BspIoUartTxData(uint8 *pu8TxData, uint16 u16Count)
{
	timer_disable(TIMER4);	
	timer_interrupt_flag_clear(TIMER4, TIMER_INT_FLAG_UP);	
	
	pu8TxBuff = pu8TxData;
	u16TxCount = u16Count;
	u16TxPos = 0;
	u8SendData = 0;
	u8SendPos = 0;
	eUartStep = eStart;
	
	timer_enable(TIMER4);	
}

void TIMER4_IRQHandler(void)
{
	if(SET == timer_interrupt_flag_get(TIMER4, TIMER_INT_FLAG_UP))
	{
		switch(eUartStep)
		{
			case eStart:
									u8SendData = pu8TxBuff[u16TxPos++];
									gpio_bit_reset(GPIOB, GPIO_PIN_9);
									eUartStep = eTransmit;
			
									break;
			
			case eTransmit:
									if((u8SendData >> u8SendPos) & 0x01)
									{
										gpio_bit_set(GPIOB, GPIO_PIN_9);
									}
									else
									{
										gpio_bit_reset(GPIOB, GPIO_PIN_9);
									}
									
									u8SendPos++;
									
									if(u8SendPos > 7)
									{
										u8SendPos = 0;
										eUartStep = eStop;
									}
			
									break;

			case eStop:
									gpio_bit_set(GPIOB, GPIO_PIN_9);
									eUartStep = eStart;
			
									if(u16TxPos >= u16TxCount)
									{
										timer_disable(TIMER4);
									}

									break;			
		}
		
		timer_interrupt_flag_clear(TIMER4, TIMER_INT_FLAG_UP);
	}
}

/************************* IO UART RX ****************************/
static void BspIoUartT3Init(void)
{
	timer_parameter_struct timer_initpara;	
	
	nvic_irq_enable(TIMER3_IRQn, 0, 0);		
	rcu_periph_clock_enable(RCU_TIMER3);	
	
	timer_deinit(TIMER3);
	timer_struct_para_init(&timer_initpara);
	
	timer_initpara.prescaler         = 0;
	timer_initpara.alignedmode       = TIMER_COUNTER_EDGE;
	timer_initpara.counterdirection  = TIMER_COUNTER_UP;
	timer_initpara.period            = UART_IO_DELAY_COUNT * 120 - 1;
	timer_initpara.clockdivision     = TIMER_CKDIV_DIV1;
	timer_init(TIMER3, &timer_initpara);

	timer_interrupt_flag_clear(TIMER3, TIMER_INT_FLAG_UP);
	timer_interrupt_enable(TIMER3, TIMER_INT_UP);		
	timer_disable(TIMER3);
}

void BspIoUartRxData(uint8 *pu8RxData, uint16 u16Count)
{
	nvic_irq_disable(EXTI5_9_IRQn);		
	timer_disable(TIMER3);	
	timer_interrupt_flag_clear(TIMER3, TIMER_INT_FLAG_UP);		
	
	pu8RxBuff = pu8RxData;
	u16RxCount = u16Count;
	u16RxPos = 0;
    u8RevData = 0;
    u8Pos = 0;	
	
	exti_interrupt_flag_clear(EXTI_8);
	nvic_irq_enable(EXTI5_9_IRQn, 0U, 0U);
}

void EXTI5_9_IRQHandler(void)
{
	if(RESET != exti_interrupt_flag_get(EXTI_8))
	{
		nvic_irq_disable(EXTI5_9_IRQn);		
		
		timer_counter_value_config(TIMER3,0);
		timer_enable(TIMER3);
		
		exti_interrupt_flag_clear(EXTI_8);
	}
}

void TIMER3_IRQHandler(void)
{  
	if(SET == timer_interrupt_flag_get(TIMER3, TIMER_INT_FLAG_UP))
	{
		if(gpio_input_bit_get(GPIOB, GPIO_PIN_8) != RESET)
		{
			u8RevData |= (1 << u8Pos); 			
		}

		u8Pos++;
		
		if(u8Pos >= 8)
		{
			pu8RxBuff[u16RxPos++] = u8RevData; 
			
			if(u16RxPos >= u16RxCount)
			{
				u16RxPos = 0;
			}
			
			u8Pos = 0;
			u8RevData = 0;
			exti_interrupt_flag_clear(EXTI_8);
			nvic_irq_enable(EXTI5_9_IRQn, 0U, 0U);
			timer_disable(TIMER3);
		}
		
		timer_interrupt_flag_clear(TIMER3, TIMER_INT_FLAG_UP);
	}
}

头文件

#ifndef _BSP_IO_UART_H
#define _BSP_IO_UART_H

#include "gd32f30x.h"
#include "basic_data_type.h"

void BspIoUartInit(void);
void BspIoUartTxData(uint8 *pu8TxData, uint16 u16Count);
void BspIoUartRxData(uint8 *pu8RxData, uint16 u16Count);

#endif