atmega328 i2c slave

#1 · March 13, 2024, 2:59 pm

Hi,

i try to use i2c slave mode using arduino lib Wire.h, but that don't work as expected.

Very simple programm :

#include <Wire.h>
const int8_t i2cAddress = 8;

void receiveEvent(int nbBytes)
{ 
	PORTD=Wire.read();
}

int main()
{
	DDRD=0xFF;
	Wire.begin(i2cAddress);
	Wire.onReceive(receiveEvent);
	sei();
	while(1)
	{
		_delay_us(100);
		//PORTD=TWDR;
	}
}

TWDR register contains right datas but callback function is not executed.

it seams TWSR register does not worked as expected. Il should take TW_SR_STOP 0xA0 value but only got TW_SR_DATA_ACK 0x80 and TW_SR_SLA_ACK 0x60

#2 · March 13, 2024, 4:00 pm

Hi.
Thanks for reporting and for the solution.

Indeed a Stop condition does not set the correct status value.
Solved at Rev 2255.

bjacquot has reacted to this post.

#3 · March 13, 2024, 4:23 pm

too late, I had just figured out how to solve this problem 🙂

thx.

arcachofo has reacted to this post.

#4 · March 21, 2024, 12:36 pm

it don't work as expected.
You should send TWI_SRX_STOP_RESTART only when the i2c message is for you :

if (m_addrMatch) setTwiState( TWI_SRX_STOP_RESTART );

#5 · March 22, 2024, 8:28 am

Thanks, solution applied at Rev 2274.