simple_uart_isr.c

altera串口源代码程序

//

#include "excalibur.h"
#include "buffer.h"  // defines RXBUFSIZE and TXBUFSIZE

//Global variables
unsigned char RxBuf[RXBUFSIZE];	// the receiver buffer.
int RxHead = 0;			// the circular buffer index
int RxTail = 0;
unsigned char TxBuf[TXBUFSIZE];	// the transmit buffer.
int TxHead = 0;			// the circular buffer index
int TxTail = 0;

unsigned char _getchar(); 
void serial_simple_ISR(int context);
int _putchar(int in_char);

int main(void)
{
	int context = 0;
	
	nr_installuserisr(na_uart1_irq, serial_simple_ISR, context);  // install UART ISR
	na_uart1->np_uartcontrol = np_uartcontrol_irrdy_mask;  // enable rx interrupts
	
	while(1)
	{
		_putchar( (int)(_getchar()) );
	}

	return 0;
}

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

void serial_simple_ISR(int data)
{
	// need to retrieve the status register
	int sr = na_uart1 ->np_uartstatus;

	if(sr & np_uartstatus_rrdy_mask)
	{	// something ready for the receiver.
 		// put new char into buffer from UART
		RxBuf[RxHead] = na_uart1->np_uartrxdata; 
		// clear the errors and interrupts
		na_uart1->np_uartstatus=0; 
		if ((++RxHead) > (RXBUFSIZE-1))		
		{
			RxHead = 0;
		}
	}	// end of receiver

	if(sr & np_uartstatus_trdy_mask)
	{	//  transmitter ready
		if(na_uart1->np_uartcontrol & np_uartcontrol_itrdy_mask)  
		{	// ready to handle transmitter interrupts
			if (TxTail != TxHead) 
			{      		
				na_uart1->np_uarttxdata = TxBuf[TxTail];   // send a byte of data
				if (++TxTail > (TXBUFSIZE -1))	// check for wrap around.
               			TxTail = 0;
			}
			else 
			{       /* tx buffer empty, disable iTRDY.  Since this ISR only deals with iTRDY 
					and iRRDY, we will accomplish this by enabling just iRRDY. */
				na_uart1->np_uartcontrol = np_uartcontrol_irrdy_mask;			
			}
		}
	}	// end of transmitter

} // end of ISR