Posted on March 28, 2014 at 10:46Hello everybody,
Please help me for this problem! I try to communicate the M24SR and M24LR to the atmega 8. I used the under code for my test. This code functions with the M24LR very well. But there is a problem for the M24SR. It's always stop by sending Address.
Please help me! Thank you !
Best regards
&sharpinclude <avr/io.h>
&sharpdefine F_CPU 8000000UL // internal oszillator 8MHz
&sharpinclude <util/delay.h>
&sharpinclude <compat/twi.h>
&sharpdefine MAX_TRIES 100
&sharpdefine EEPROM_ADDR 0xAC // EEPROM Device Address M24SR = 0xAC, M24LR = 0xA6
&sharpdefine I2C_START 0
&sharpdefine I2C_DATA 1
&sharpdefine I2C_STOP 2
unsigned char i2c_transmit(unsigned char type) {
switch(type) {
case I2C_START: // Send Start Condition
TWCR = (1 << TWINT) | (1 << TWSTA) | (1 << TWEN);
break;
case I2C_DATA: // Send Data
TWCR = (1 << TWINT) | (1 << TWEN);
break;
case I2C_STOP: // Send Stop Condition
TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO);
return 0;
}
// Wait for TWINT flag set in TWCR Register
while (!(TWCR & (1 << TWINT)));
// Return TWI Status Register, mask the prescaler bits (TWPS1,TWPS0)
return (TWSR & 0xF8);
}
//int i2c_writebyte(unsigned int i2c_address, unsigned int dev_id,unsigned int dev_addr,char data)
int i2c_writebyte(unsigned int i2c_address,unsigned int dev_addr,char data)
{
unsigned char n = 0;
unsigned char twi_status;
char r_val = -1;
i2c_retry:
if (n++ >= MAX_TRIES) return r_val;
// Transmit Start Condition
twi_status=i2c_transmit(I2C_START);
// Check the TWI Status
if (twi_status == TW_MT_ARB_LOST) goto i2c_retry;
if ((twi_status != TW_START) && (twi_status != TW_REP_START)) goto i2c_quit;
// Send slave address (SLA_W)
TWDR = dev_addr | TW_WRITE;
// Transmit I2C Data
twi_status=i2c_transmit(I2C_DATA);
// Check the TWSR status
if ((twi_status == TW_MT_SLA_NACK) || (twi_status == TW_MT_ARB_LOST)) goto i2c_retry;
if (twi_status != TW_MT_SLA_ACK) goto i2c_quit;
// Send the High 8-bit of I2C Address
TWDR = i2c_address >> 8;
// Transmit I2C Data
twi_status=i2c_transmit(I2C_DATA);
// Check the TWSR status
if (twi_status != TW_MT_DATA_ACK) goto i2c_quit;
// Send the Low 8-bit of I2C Address
TWDR = i2c_address;
// Transmit I2C Data
twi_status=i2c_transmit(I2C_DATA);
// Check the TWSR status
if (twi_status != TW_MT_DATA_ACK) goto i2c_quit;
// Put data into data register and start transmission
TWDR = data;
// Transmit I2C Data
twi_status=i2c_transmit(I2C_DATA);
// Check the TWSR status
if (twi_status != TW_MT_DATA_ACK) goto i2c_quit;
// TWI Transmit Ok
r_val=1;
i2c_quit:
// Transmit I2C Data
twi_status=i2c_transmit(I2C_STOP);
return r_val;
}
int main(void)
{
char buffer[5]= {0x34,0x56,0xff,0x12,0x45};
char data;//id1,id2;
unsigned int dev_address,i;
DDRB=0xFF; // Set PORTB as Output
PORTB=0x00; // Set All PORTB to Low
/* Initial TWI Peripheral */
TWSR = 0x00; // Select Prescaler of 1
// SCL frequency = 11059200 / (16 + 2 * 48 * 1) = 98.743 khz
TWBR = 0x30; // 48 Decimal
TWCR = (1<<TWEA)|(1<<TWEN)|(1<<TWIE); //Ack is set, TWI, Intermptis ENABLE
// Read the EEPROM ID
dev_address=0; // Start at Address 0
for(i=0;i < 5;i++) {
i2c_writebyte(dev_address + i,EEPROM_ADDR,buffer[i]);
//i2c_writebyte(dev_address + i,EEPROM_ID,EEPROM_ADDR,buffer[i]);
int y;
for (y=0;y<100;y++);
}
return 0;
}
#i2c #m24sr
