twi1.c

AVR单片机中TWI(I2C)总线操作串行存储器24c02的C语言程序,如果要搞TWI串行总线的可以参考.程序总包括了单片机对24c02的写和读,用ICCAVR开发.

/*
	I2C总线/TWI操作模块
	1、读取和写入函数
	2、地址有效范围255
	3、数据长度为单字节
	4、函数采用查询方式
	5、可直接嵌入到项目中使用
	6、晶振频率：1M
	7、总线速度：50K

	AVR_AFA
*/

#include "iom16v.h"

extern unsigned char twi_write(unsigned char addr, unsigned char dd);
extern unsigned char twi_read(unsigned char addr, unsigned char *dd);

/*延时函数*/
void delay_ms(unsigned char i) 
	{

	unsigned char a, b;
	for (a = 1; a < i; a++) {
		for (b = 1; b; b++) {
			;
			}
		}
	}

/*I2C总线主机模式错误处理*/
void error(unsigned char type) 
	{
	switch (type & 0xF8) 
		{
		case 0x20:					/*址址写失败*/
			/*stop 停止*/
			TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO);
			break;
		case 0x30:					/*数据写失败*/
			/*stop 停止*/
			TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO);
			break;
		case 0x38:					/*仲裁失败*/
			break;
		case 0x48:					/*址址读失败*/
			/*stop 停止*/
			TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO);
			break;
		}
	}

/*I2C总线单字节写入*/
unsigned char twi_write(unsigned char addr, unsigned char dd) 
	{
	TWBR = 2;

	/*start 启动*/
	TWCR = (1 << TWINT) | (1 << TWSTA) | (1 << TWEN);
	while (!(TWCR & (1 << TWINT)));
	if ((TWSR & 0xF8) != 0x08) 
		{
		error(TWSR);
		return 0;
		}

	/*SLA_W 芯片地址*/
	TWDR = 0xA0;
	TWCR = (1 << TWINT) | (1 << TWEN);
	while (!(TWCR & (1 << TWINT)));
	if ((TWSR & 0xF8) != 0x18) 
		{
		error(TWSR);
		return 0;
		}

	/*addr 操作地址*/
	TWDR = addr;
	TWCR = (1 << TWINT) | (1 << TWEN);
	while (!(TWCR & (1 << TWINT)));
	if ((TWSR & 0xF8) != 0x28) 
		{
		error(TWSR);
		return 0;
		}
	
	/*dd 写入数据*/
	TWDR = dd;
	TWCR = (1 << TWINT) | (1 << TWEN);
	while (!(TWCR & (1 << TWINT)));
	if ((TWSR & 0xF8) != 0x28) 
		{
		error(TWSR);
		return 0;
		}
	
	/*stop 停止*/
	TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO);
	return 1;
	}

/*I2C总线单字节读取*/
unsigned char twi_read(unsigned char addr, unsigned char *dd) 
	{
	TWBR = 2;

	/*start 启动*/
	TWCR=(1<<TWINT)|(1<<TWSTA)|(1<<TWEN);
	while(!(TWCR&(1<<TWINT)));
	if ((TWSR & 0xF8) != 0x08) 
		{
		error(TWSR);
		return 0;
		}

	/*SLA_W 芯片地址*/
	TWDR = 0xA0;
	TWCR = (1 << TWINT) | (1 << TWEN);
	while (!(TWCR & (1 << TWINT)));
	if ((TWSR & 0xF8) != 0x18) 
		{
		error(TWSR);
		return 0;
		}

	/*addr 操作地址*/
	TWDR = addr;
	TWCR = (1 << TWINT) | (1 << TWEN);
	while (!(TWCR & (1 << TWINT)));
	if ((TWSR & 0xF8) != 0x28) 
		{
		error(TWSR);
		return 0;
		}
		
	/*start 启动*/
	TWCR = (1 << TWINT) | (1 << TWSTA) | (1 << TWEN);
	while (!(TWCR & (1 << TWINT)));
	if ((TWSR & 0xF8) != 0x10) 
		{
		error(TWSR);
		return 0;
		}
	
	/*SLA_R 芯片地址*/
	TWDR = 0xA1;
	TWCR = (1 << TWINT) | (1 << TWEN);
	while (!(TWCR & (1 << TWINT)));
	if ((TWSR & 0xF8) != 0x40) 
		{
		error(TWSR);
		return 0;
		}

	/*读取数据*/
	TWCR = (1 << TWINT) | (1 << TWEN);
	while (!(TWCR & (1 << TWINT)));
	if ((TWSR & 0xF8) != 0x58) 
		{
		error(TWSR);
		return 0;
		}
	*dd = TWDR;
		
	/*stop 停止*/
	TWCR = (1 << TWINT) | (1 << TWSTO) | (1 << TWEN);
	return 1;
}
/*主函数*/
void main(void) 
	{

	unsigned char temp;

	PORTA = 0xFF;				/*打开上拉*/
	DDRA = 0x00;				/*方向输入*/
	PORTB = 0xF0;				/*电平设置*/
	DDRB = 0xFF;				/*方向输出*/
	PORTC = 0xFF;
	DDRC = 0x00;
	PORTD = 0xFF;
	DDRD = 0x00;
	
	twi_read(0x08, &temp);
	PORTB = ~temp;
	temp ++;
	twi_write(0x08, temp);

	while (1) 
		{
		;
		}
	}