/*
 I2C總線/TWI操作模塊
 1、讀取和寫入函數(shù)
 2、地址有效范圍255
 3、數(shù)據(jù)長度為單字節(jié)
 4、函數(shù)采用查詢方式
 5、可直接嵌入到項目中使用
 6、晶振頻率：1M
 7、總線速度：50K
 AVR_AFA
 www.iccavr.com
*/
#include "iom128v.h"
/*I2C總線主機(jī)模式錯誤處理*/
void error(unsigned char type) 
{
 switch (type & 0xF8) 
 {
  case 0x20:     /*址址寫失敗*/
   /*stop 停止*/
   TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO);
   break;
  case 0x30:     /*數(shù)據(jù)寫失敗*/
   /*stop 停止*/
   TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO);
   break;
  case 0x38:     /*仲裁失敗*/
   break;
  case 0x48:     /*址址讀失敗*/
   /*stop 停止*/
   TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO);
   break;
  }
}
/*I2C總線單字節(jié)寫入*/
unsigned char twi_write(unsigned char addr, unsigned char dd) 
{
 TWBR = 2;
 /*start 啟動*/
 TWCR = (1 << TWINT) | (1 << TWSTA) | (1 << TWEN);                              //發(fā)送START信號
 while (!(TWCR & (1 << TWINT)));                                                //等待TWINT置位，TWINT置位表示START信號已發(fā)出
 if ((TWSR & 0xF8) != 0x08) {
  error(TWSR);
  return 0;
  }
 /*SLA_W 芯片地址*/
 TWDR = 0xA0;
 TWCR = (1 << TWINT) | (1 << TWEN);                                             //TWINT位清零，啟動發(fā)送地址
 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 寫入數(shù)據(jù)*/
 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總線單字節(jié)讀取*/
unsigned char twi_read(unsigned char addr, unsigned char *dd) 
{
 TWBR = 2;
 /*start 啟動*/
 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 啟動*/
 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;
  }
 /*讀取數(shù)據(jù)*/
 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;
}