usart0_setup.c

UART developing tutorial module with source codes a褌胁 hints.

	//	|-----------------------------------------------------------------------|
	//   31                                                                   24      
	//
	//	|-----------------------------------------------------------------------|
	//	|                                                                       |
	//	|-----------------------------------------------------------------------|
	//   23                                                                   16      
	//
	//	|-----------------------------------------------------------------------|
	//	|                                                                       |
	//	|-----------------------------------------------------------------------|
	//   15                                                                    8      
	//
	//	|-----------------------------------------------------------------------|
	//	|                           NB_ERRORS                                   |
	//	|-----------------------------------------------------------------------|
	//   7                                                                     0      
	//  Read-only, nothing to set up here
	
	
	
	//		USART0 IrDA Filter Register  US_IF   (read/write)
	//	|-----------------------------------------------------------------------|
	//	|                                                                       |
	//	|-----------------------------------------------------------------------|
	//   31                                                                   24      
	//
	//	|-----------------------------------------------------------------------|
	//	|                                                                       |
	//	|-----------------------------------------------------------------------|
	//   23                                                                   16      
	//
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	//	|                                                                       |
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	//   15                                                                    8      
	//
	//	|-----------------------------------------------------------------------|
	//	|                           IRDA_FILTER                                 |
	//	|-----------------------------------------------------------------------|
	//   7                                                                     0      
	//  not used, nothing to set up here
	
	
	// ---------------------------------------------------
	//  The following are the DMA registers for the USART0
	// ---------------------------------------------------
	
	//		USART0 PDC Receive Pointer Register  US_RPR   (read/write)
	//	|-----------------------------------------------------------------------|
	//	|                            RXPTR                                      |
	//	|-----------------------------------------------------------------------|
	//   31                                                                    0      
	//  
	pUsart0->US_RPR = (unsigned int)Buffer;						// address of DMA input buffer
	

	
	//		USART0 PDC Receive Counter Register  US_RCR   (read/write)
	//	|-----------------------------------------------------------------------|
	//	|                                                                       |
	//	|-----------------------------------------------------------------------|
	//   31                                                                   16      
	//  
	//	|-----------------------------------------------------------------------|
	//	|                            RXCTR                                      |
	//	|-----------------------------------------------------------------------|
	//   15                                                                    0      
	//  
	pUsart0->US_RCR = 10;				// we'll read in 10 chars via DMA
	
	
	//		USART0 PDC Transmit Pointer Register  US_TPR   (read/write)
	//	|-----------------------------------------------------------------------|
	//	|                            TXPTR                                      |
	//	|-----------------------------------------------------------------------|
	//   31                                                                    0      
	//  
	pUsart0->US_TPR = (unsigned int)Buffer;			// address of DMA output buffer (use same one)
	

	
	//		USART0 PDC Transmit Counter Register  US_TCR   (read/write)
	//	|-----------------------------------------------------------------------|
	//	|                                                                       |
	//	|-----------------------------------------------------------------------|
	//   31                                                                   16      
	//  
	//	|-----------------------------------------------------------------------|
	//	|                            TXCTR                                      |
	//	|-----------------------------------------------------------------------|
	//   15                                                                    0      
	//  
	pUsart0->US_TCR = 10;				// we'll transmit 10 chars via DMA
	
	

//		USART0 PDC Receive Next Pointer Register  US_RNPR   (read/write)
//	|-----------------------------------------------------------------------|
//	|                            RXNPTR                                     |
//	|-----------------------------------------------------------------------|
//   31                                                                    0      
//
	pUsart0->US_RNPR = (unsigned int)0;			// next DMA receive buffer address
												// if set to zero, it is not used
	


//		USART0 PDC Receive NextCounter Register  US_RNCR   (read/write)
//	|-----------------------------------------------------------------------|
//	|                                                                       |
//	|-----------------------------------------------------------------------|
//   31                                                                   16      
// 
//	|-----------------------------------------------------------------------|
//	|                            RXNCR                                     |
//	|-----------------------------------------------------------------------|
//   15                                                                    0      
//  
	pUsart0->US_RNCR = (unsigned int)0;			// next DMA receive counter
												// if set to zero, it is not used


//		USART0 PDC Transmit Next Pointer Register  US_TNPR   (read/write)
//	|-----------------------------------------------------------------------|
//	|                            TXNPTR                                     |
//	|-----------------------------------------------------------------------|
//   31                                                                    0      
//  
	pUsart0->US_TNPR = (unsigned int)0;			// next DMA transmit buffer address
												// if set to zero, it is not used
	


//		USART0 PDC Transmit NextCounter Register  US_TNCR   (read/write)
//	|-----------------------------------------------------------------------|
//	|                                                                       |
//	|-----------------------------------------------------------------------|
//   31                                                                   16      
//  
//	|-----------------------------------------------------------------------|
//	|                            TXNCR                                      |
//	|-----------------------------------------------------------------------|
//   15                                                                    0      
//  
	pUsart0->US_TNCR = (unsigned int)0;			// next DMA transmit counter
												// if set to zero, it is not used



	//		USART0 PDC Transfer Control Register  US_PTCR   (write-only)
	//	|-----------------------------------------------------------------------|
	//	|                                                                       |
	//	|-----------------------------------------------------------------------|
	//   31                                                                   16      
	//
	//	|--------|--------|--------|--------|--------|--------|--------|--------|
	//	|                                                       TXTDIS   TXTEN  |
	//	|--------|--------|--------|--------|--------|--------|--------|--------|
	//      15       14       13       12       11       10        9        8         
	//
	//	|--------|--------|--------|--------|--------|--------|--------|--------|
	//	|                                                       RXTDIS   RXTEN  |
	//	|--------|--------|--------|--------|--------|--------|--------|--------|
	//       7          6      5        4        3        2        1        0         
	//
	//	RXTEN = 1					// receiver transfer enable (enabled)
	//	RXTDIS = 0					// receiver transfer disable (no effect)
	//	TXTEN = 0					// transmitter transfer enable (no effectd)
	//	TXTDIS = 1					// transmitter transfer disable (disabled)
	//
	pUsart0->US_PTCR =	AT91C_PDC_RXTEN | 	// enable receive transfer,
						AT91C_PDC_TXTDIS;	// disable transmit transfer
						
	
	
	// Set up the Advanced Interrupt Controller (AIC)  registers for USART0  
	volatile AT91PS_AIC	pAIC = AT91C_BASE_AIC;			// pointer to AIC data structure
	pAIC->AIC_IDCR = (1<<AT91C_ID_US0);					// Disable USART0 interrupt in AIC Interrupt Disable Command Register			
	pAIC->AIC_SVR[AT91C_ID_US0] =						// Set the USART0 IRQ handler address in AIC Source 
    	(unsigned int)Usart0IrqHandler;        			// Vector Register[6]
	pAIC->AIC_SMR[AT91C_ID_US0] =						// Set the interrupt source type and priority 
   		(AT91C_AIC_SRCTYPE_INT_HIGH_LEVEL | 0x4 ); 		// in AIC Source Mode Register[6]
	pAIC->AIC_IECR = (1<<AT91C_ID_US0); 				// Enable the USART0 interrupt in AIC Interrupt Enable Command Register
	
	// enable the USART0 receiver and transmitter
	pUsart0->US_CR = AT91C_US_RXEN | AT91C_US_TXEN;
	
	// enable the USART0 end-of-receive interrupt
	pUsart0->US_IER = AT91C_US_ENDRX;					// enable ENDRX usart0 end-of-receive interrupt
	pUsart0->US_IDR = ~AT91C_US_ENDRX;					// disable all interrupts except ENDRX
	

	// at this point, only the USART0 end-of-receive interrupt is armed!
	// note: this means that incoming characters will not cause an interrupt until the 10th
	//       character is received.
}