interrupt_usart.c

ARM入门的好帮手.包含了从简单到相对较复杂的程序.

//*----------------------------------------------------------------------------
//*      ATMEL Microcontroller Software Support  -  ROUSSET  -
//*----------------------------------------------------------------------------
//* The software is delivered "AS IS" without warranty or condition of any
//* kind, either express, implied or statutory. This includes without
//* limitation any warranty or condition with respect to merchantability or
//* fitness for any particular purpose, or against the infringements of
//* intellectual property rights of others.
//*----------------------------------------------------------------------------
//* File Name           : interrupt_Usart.c
//* Object              : USART Interrupt Management
//*
//* 1.0 03/Jan/03 JPP   : Creation
//*----------------------------------------------------------------------------

// Include Standard LIB  files 
#include "eb40A.h"

extern void usart_asm_irq_handler(void);
#define USART_INTERRUPT_LEVEL		7
#define US_SPEED			9600
#define TIMEOUT				50
#define AT91C_US_USMODE_NORMAL	AT91C_US_CHMODE_NORMAL

static const char atmel_header[]=
{
"\n\r  *** ATMEL Usart IRQ ***\n\r"
"Copyright (C) 2003 ATMEL Corporations Version: 1.0\n\r"
};

char message[80];
AT91PS_USART COM0;

//*------------------------- Internal Function --------------------------------
//*------------------------- Interrupt Function -------------------------------

//*----------------------------------------------------------------------------
//* Function Name       : Usart_c_irq_handler
//* Object              : C handler interrupt function called by the interrupts 
//*                       assembling routine
//* Input Parameters    : <RTC_pt> time rtc descriptor
//* Output Parameters   : increment count_timer0_interrupt
//*----------------------------------------------------------------------------
void Usart_c_irq_handler(AT91PS_USART USART_pt)
{
	unsigned int status;
	//* get Usart status register
	status = USART_pt->US_CSR & USART_pt->US_IMR;
	
	if ( status & AT91C_US_RXRDY ){
              // trace the reception
                 AT91F_US_PutChar (USART_pt, 'R');
              // Disabe RXRDY
                 AT91F_US_DisableIt(USART_pt,AT91C_US_RXRDY);
              // Enabel ENDTX
                 AT91F_US_EnableIt(USART_pt,AT91C_US_ENDRX);
              // Set PDC
                 AT91F_US_ReceiveFrame(USART_pt,(char *)message,10); 
	}
	
	if ( status & AT91C_US_ENDRX){
              // Disabe ENDTX
                 AT91F_US_DisableIt(COM0,AT91C_US_ENDRX);
              // Enabel RXRDY
                 AT91F_US_EnableIt(COM0,AT91C_US_RXRDY);
              // Trace the reception
		 AT91F_US_PutChar (USART_pt, 'E');
	}

	// check if interrupt is present and available 
	if ( (status & AT91C_US_ENDTX) &  (USART_pt->US_IMR & AT91C_US_ENDTX) ){
		 //*  Acknowledge Interrupt by mask for next send
		 AT91F_US_DisableIt(USART_pt, AT91C_US_ENDTX );
		 //* wait the end usart transmit last PDC char
		 while (  ( USART_pt->US_CSR & AT91C_US_TXRDY ) != AT91C_US_TXRDY){};
		//* Get byte and send
		 AT91F_US_PutChar (USART_pt, 'i');
	}
	
	if ( status & AT91C_US_OVRE) {
		//* clear US_RXRDY
		 AT91F_US_GetChar(USART_pt);
		 AT91F_US_PutChar (USART_pt, 'O');
	}

	//* Check error
	if ( status & AT91C_US_PARE) {
		 AT91F_US_PutChar (USART_pt, 'P');
	}

	if ( status & AT91C_US_FRAME) {
		 AT91F_US_PutChar (USART_pt, 'F');
	}

	if ( status & AT91C_US_TIMEOUT){
		USART_pt->US_CR = AT91C_US_STTTO;
		 AT91F_US_PutChar (USART_pt, 'T');
	}

	//* Reset the satus bit
	 USART_pt->US_CR = AT91C_US_RSTSTA;
}
//*-------------------------- External Function -------------------------------

//*----------------------------------------------------------------------------
//* Function Name       : Usart_init
//* Object              : USART initialization 
//* Input Parameters    : none
//* Output Parameters   : TRUE
//*----------------------------------------------------------------------------
void Usart_init ( void )
//* Begin
{
	
	COM0= AT91C_BASE_US1;

    // Define RXD and TXD as peripheral
       AT91F_PIO_CfgPeriph(AT91C_BASE_PIO,AT91C_P22_RXD1 | AT91C_P21_TXD1,0);

    // First, enable the clock 
       AT91F_PS_EnablePeriphClock ( AT91C_BASE_PS, 1<<AT91C_ID_US1 ) ;
	
    // Reset receiver and transmitter
       COM0->US_CR = AT91C_US_RSTRX | AT91C_US_RSTTX;

    // Reset Status Bits (PARE, FRAME, OVRE and RXBRK)
       COM0->US_CR = AT91C_US_RSTSTA;

    // Usart Configure
       AT91F_US_Configure (COM0, MCK,AT91C_US_ASYNC_MODE, US_SPEED, 0);
	
    // Enable usart 
        COM0->US_CR = AT91C_US_RXEN | AT91C_US_TXEN;
    	
    // Enable USART IT error and AT91C_US_ENDRX
       AT91F_US_EnableIt(COM0,AT91C_US_TIMEOUT | AT91C_US_FRAME | AT91C_US_OVRE |AT91C_US_RXRDY);

    // open Usart 1 interrupt
       AT91F_AIC_ConfigureIt ( AT91C_BASE_AIC, AT91C_ID_US1, USART_INTERRUPT_LEVEL,AT91C_AIC_SRCTYPE_INT_LEVEL_SENSITIVE, usart_asm_irq_handler); 
       AT91F_AIC_EnableIt (AT91C_BASE_AIC, AT91C_ID_US1); 

    // Wait for USART CLOCK ready
	while ( !( COM0->US_CSR & AT91C_US_TXRDY ));
	
   //* Arm time out after 255 * 4  bits time 
	COM0->US_RTOR = TIMEOUT;
   // *Enable usart SSTO
	COM0->US_CR = AT91C_US_STTTO;
		
    //* first
 	AT91F_US_SendFrame(COM0,(char *)atmel_header,sizeof(atmel_header));
   	AT91F_US_EnableIt(COM0, AT91C_US_ENDTX );
	
//* End
}