通过I/O方式模拟串口接收

通过I/O模拟串口方式是通过定时器 定时扫描I/O口电平，

void GPCDE_IRQHandler(void)  //下降沿中断，打开定时计数
{
	if(GPIOD->ISRC & 0x0040) {
		TIMER0->TCSR.CEN = 1;
	}
}

void TMR0_IRQHandler(void)
{
	volatile uchar vmCRS232;
	TISR.TIF =1;
	vmCRS232 = VM_UART_RX;   // #define VM_UART_RX             (GPIOD6_PIN)
	VM_Uart3_RX(vmCRS232);
}

void VM_Uart3_RX(uchar dataBit) // 模拟UART接收函数 
{ 
	static uchar GpsDotCnt=0;
	static uchar status = START;     
	static uchar cnt = 0;     
	static uchar number = 0;     
	static uchar rData; 
	    
    switch(status) 
	{         
		case START:
			if(dataBit) 
			{ 
				cnt = 0;
			} 
			else 
			{ 
				if(++cnt > 0)  
				{ 
					cnt = 0; 
					number = 0; 
					status = SDATA; 
				} 
			}
			break; 
		case SDATA: 
			if(++cnt > 3) 
			{ 
				cnt = 0; 
				if(dataBit) 
				{ 
					rData |= 0x80;
				} 
				else 
				{
					rData &= 0x7F;
				} 
				if(++number < 8) 
				{ 
					rData >>= 1;
				} 
				else 
				{ 
					number = 0; 
					status = STOP; 
				} 
			}
		break; 
		case STOP:if(++cnt > 2) 
			{ 
				cnt = 0; 
				TIMER0->TCSR.CEN = 0;
				DrvGPIO_EnableInt(E_GPD, 6, E_IO_FALLING, E_MODE_EDGE);
			    if(dataBit) 
			    { 
					//数据操作
				}
				status = START;
			}
			break; 
		default:
		{
			cnt = 0; 
			status = START;
		}
		break; 
	} 
}