twi.c

ATMEL ATSAM7S64处理器部分控制程序。

/*********************************************************************************************
* File：	twi.c
* Author:	Embest z.j.zheng
* Desc：	write the 0-f to the at24c02,then read out.
* History:	
*********************************************************************************************/
/*------------------------------------------------------------------------------------------*/
/*								include files												*/
/*------------------------------------------------------------------------------------------*/
#include "Board.h"

/*------------------------------------------------------------------------------------------*/
/*								Global variable										 		*/
/*------------------------------------------------------------------------------------------*/
char data_out[16];
AT91PS_USART COM0;

/*------------------------------------------------------------------------------------------*/
/*								constent definition											*/
/*------------------------------------------------------------------------------------------*/
#define USART_INTERRUPT_LEVEL		7
#define USART_BAUD_RATE				115200

/*********************************************************************************************
* name:		time_dly
* func:		display code
* para:		dly			--in, delay value
* ret:		none
* modify:
* comment:		
*********************************************************************************************/
void  time_dly(int  dly)
{  
	int  i;

	for(; dly>0; dly--) 
		for(i=0; i<500; i++);
}

/*********************************************************************************************
* name:		init_twi
* func:		
* para:		none
* ret:		none
* modify:
* comment:	
*********************************************************************************************/

init_twi(void)
{

	// Configure PIO controllers to periph mode, in open drain
	AT91F_TWI_CfgPIO();        
	AT91F_PIO_CfgOpendrain(AT91C_BASE_PIOA,AT91C_PA3_TWD | AT91C_PA4_TWCK);
	
	// AT91F_PMC_EnablePeriphClock ( AT91C_BASE_PMC, 1 << AT91C_ID_PIOA ) ;
	AT91F_TWI_CfgPMC();

	AT91F_TWI_DisableIt(AT91C_BASE_TWI,-1);                     // Disable TWI IT
	AT91F_TWI_Configure(AT91C_BASE_TWI);                        // Configure TWI in master mode
}

/*********************************************************************************************
* name:		Usart_init
* func:		USART initialization
* para:		none		
* ret:		none
* modify:
* comment:		
*********************************************************************************************/
void Usart_init ( void )
{

	COM0= AT91C_BASE_US0;

	// Define RXD and TXD as peripheral
	AT91F_US0_CfgPIO() ;

	// First, enable the clock of the PIOB
	AT91F_PMC_EnablePeriphClock ( AT91C_BASE_PMC, 1<<AT91C_ID_US0 ) ;

	// Usart Configure
	AT91F_US_Configure (COM0, MCK,AT91C_US_ASYNC_MODE,USART_BAUD_RATE , 0);

	// Enable usart
	COM0->US_CR = AT91C_US_RXEN | AT91C_US_TXEN;


   // ------ set time out US_RTOR
   // Arm time out after 255 * 4  bits time
   // for 115200 bit time = 1/115200 = 8.6 micro sec time out unuti= 4* 8.6 = 34 micro
   //
	COM0->US_RTOR = 0xFFFF;

}

/*********************************************************************************************
* name:		AT91F_US_Printk
* func:		This function is used to send a string through the US channel
* para:				
* ret:		none
* modify:
* comment:		
*********************************************************************************************/
void AT91F_US_Printk( char *buffer)                          // pointer to a string ending by 
{
	while(*buffer != '\0') {
		while (!AT91F_US_TxReady(COM0));
		AT91F_US_PutChar(COM0, *buffer++);
	}
}

/*********************************************************************************************
* name:		twi_write
* func:		write the data to the eeprom by the twi
* para:		pointer. pointer to the array
* ret:		none
* modify:
* comment:	
*********************************************************************************************/

void twi_write( AT91PS_TWI pTWI,int Numn)
{ 	

	AT91C_BASE_TWI->TWI_CWGR = 0x40f0f;
	pTWI->TWI_CR = AT91C_TWI_MSEN;		
	pTWI->TWI_MMR = (AT91C_TWI_IADRSZ_1_BYTE | (!AT91C_TWI_MREAD) | AT91C_TWI_DADR);
	pTWI->TWI_IADR = 0x0 + Numn;                                //INTERNAL ADDRESS 
	pTWI->TWI_THR =Numn;

	pTWI->TWI_CR = AT91C_TWI_START;                             //start
	while(pTWI->TWI_SR&0x4==0 ){};
	// must have a short delay when corresponding to the at24c02 
	time_dly(100);					
	pTWI->TWI_CR = AT91C_TWI_STOP ;                            //stop
	while(pTWI->TWI_SR&0x1==0){};
	
}

/*********************************************************************************************
* name:		twi_read
* func:		read the data from the eeprom by the twi
* para:		none
* ret:		none 
* modify:
* comment:	
*********************************************************************************************/
void twi_read(AT91PS_TWI pTWI,int n)
{	

	AT91C_BASE_TWI->TWI_CWGR = 0x40f0f;
	AT91C_BASE_TWI->TWI_CR = AT91C_TWI_MSEN | AT91C_TWI_SVDIS;
	pTWI->TWI_MMR = (AT91C_TWI_IADRSZ_1_BYTE | AT91C_TWI_MREAD | AT91C_TWI_DADR);
	
	pTWI->TWI_IADR = 0x0+n;                                     //INTERNAL ADDRESS 
	pTWI->TWI_CR |= AT91C_TWI_START;	                        //start

	while((pTWI->TWI_SR & 0x2) == 0 ){};
	data_out[n] = pTWI->TWI_RHR;
	// must have a short delay when corresponding to the at24c02 
	time_dly(100);

	pTWI->TWI_CR |= AT91C_TWI_STOP;	                            //stop
	while((pTWI->TWI_SR & 0x1) == 0){};
	
}

/*********************************************************************************************
* name:		Main
* func:		main fun
* para:		none
* ret:		none
* modify:
* comment:	
*********************************************************************************************/
 Main( void )
{

	int  i;
	init_twi();
	Usart_init();

	AT91F_US_Printk("\n\r--twi operation example--\n\r");
	AT91F_US_Printk("Write char 0-f into AT24C02\n\r");
	for(i = 0; i <= 15; i++)
	{
	twi_write(AT91C_BASE_TWI,i);                                //write the i number into the at24c02
	twi_read(AT91C_BASE_TWI,i);                                 //read the i number out from the at24c02
	}
	
	for(i = 0; i < 10; i++)                                     //change into ASCII 
	data_out[i] += '0'; 
	for(i = 10; i < 16; i++)	
	data_out[i] += 'a'-10; 	
	data_out[16] = '\0';
	
	AT91F_US_Printk("Read 16 bytes from AT24C02\n\r");	
	AT91F_US_Printk(data_out);
	do
	{
	}while(1);
}