I2C protocol ACK problem

[s.manisrinivas]

hi friends,i am using eeprom 24c64 and atmega32 avrstudio.

after 7-bit address and r/w 1-bit ,master is  acknowledging (ack 0x18) , but data 8-bit and 1-bit for ack (0x28)  is not getting ,if you give NACK (0x30) i  am getting .

 

my doubt is after data i.e. 8-bit and 1-bit ack ,master has to ack or is it okay master gives NACK also.

 

unsigned char i2c_sendData(unsigned char data)

{

 

TWDR = data;

TWCR = (1<<TWINT) |(1<<TWEN);   //Load SLA_W into TWDR Register. Clear TWINT bit

//in TWCR to start transmission of data

while (!(TWCR & (1<<TWINT)));   //Wait for TWINT flag set. This indicates that the

//data has been transmitted, and

//ACK/NACK has been received.

 

if ((TWSR & 0xF8) != MT_DATA_NACK)   //Check value of TWI Status Register

return(0);

else

return(1);

}

if you give (mt_data_Nack) it is returning 0 if you give (mt_data_ack) it returning 1.why?

[GANEEV SINGH]

Hi

There is no such predefined status "MT_DATA_NACK". It is either MT_SLA_ACK (slave's address acknowledgement) or MT_SLA_DATA (data achnowledgement).

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