AVR Freaks

The TWI registers and functionality are no different between the 402 and the 412. My chip is labelled 402. I'm not concerned about the software bug for now, it's not the source of my problem. Thanks for the heads up though. I encountered the same TWI issue with the 814; there is no way to issue a stop sequence from the TWI hardware.

I don't need that "your functions a poorly written" bullcrap. The functions aren't returning because they get stuck waiting for data from the I2C ADC. I'm competent enough with the debugger and an oscilloscope to work out that the issue is with the hardware not sending stop sequences.

My question remains, has anyone here got the TWI hardware on the 1-series to work properly, without needing to take over the IO at any point?

I'm currently working remote and have very poor internet. I can't use the Atmel Start right now because it requires a decent internet connection.

I've succeeded in getting the TWI hardware to work in polled mode. I've tested this with an ATTiny402 and an ATTiny416, using a DS3231 and an LTC2487. I've attached the library files for others to refer to.

I believe the issues I encountered were due to the Quick Command feature, and attempting to read before waiting for the RIF interrupt flag.

#include <avr/io.h>


void TWI_Init(char baud)
{
	TWI0.MBAUD = baud;
	TWI0.MCTRLB |= TWI_FLUSH_bm;
	TWI0.MSTATUS |= (TWI_RIF_bm | TWI_WIF_bm);
}

void TWI_Enable()
{
	TWI0.MCTRLA = 1<<TWI_SMEN_bp | 1 << TWI_ENABLE_bp;
	TWI0_MSTATUS |= TWI_BUSSTATE_IDLE_gc;
}

char TWI_Start(char addr)
{
	if ((TWI0.MSTATUS & TWI_BUSSTATE_gm) != TWI_BUSSTATE_BUSY_gc)
	{
		TWI0.MCTRLB &= ~(1<<TWI_ACKACT_bp);
		TWI0.MADDR = addr;
		
		if (addr & 1)
		{
			while (!(TWI0_MSTATUS & TWI_RIF_bm));
		}
		else
		{
			while (!(TWI0_MSTATUS & TWI_WIF_bm));
		}
		return TWI0.MSTATUS;
	}
	else
		return TWI0.MSTATUS;
}

char TWI_Read(char * c, char ACKorNACK)
{
	if ((TWI0.MSTATUS & TWI_BUSSTATE_gm)==TWI_BUSSTATE_OWNER_gc)
	{
		while (!(TWI0.MSTATUS & TWI_RIF_bm));
		
		if (ACKorNACK)
		TWI0.MCTRLB &= ~(1<<TWI_ACKACT_bp);	//Send ACK
		else
		TWI0.MCTRLB |= 1<<TWI_ACKACT_bp;	//Send NACK
		
		*c = TWI0.MDATA;
		
		return TWI0.MSTATUS;
	}
	else
		return TWI0.MSTATUS;
}

char TWI_Write(char data)
{
	if ((TWI0.MSTATUS&TWI_BUSSTATE_gm) == TWI_BUSSTATE_OWNER_gc)
	{
		while (!((TWI0.MSTATUS & TWI_WIF_bm) | (TWI0_MSTATUS & TWI_RXACK_bm)));
		
		TWI0.MDATA = data;
		return TWI0.MSTATUS;
	}
	else
		return TWI0.MSTATUS;
}

void TWI_Stop()
{
	TWI0.MCTRLB |= TWI_MCMD_STOP_gc;
}

Hi,

No problem. Here's how I've used it for talking to as DS3231 (ignore the Atmel Start stuff, I just used it for it uart):

#include <atmel_start.h>
#include <stdio.h>

#include "I2C.h"

#define DS3231_ADDR 0xD0


char s,m,h;
volatile char trigger;
volatile char t[10];

ISR(TCA0_OVF_vect)
{
	TCA0_SINGLE_INTFLAGS = 1;	//Clear OVF.
	trigger=1;
}

int main(void)
{
    /* Initializes MCU, drivers and middleware */
    atmel_start_init();
    
    TCA0_SINGLE_CTRLA = 1<<TCA_SINGLE_CLKSEL2_bp | 1<<TCA_SINGLE_ENABLE_bp;
    TCA0_SINGLE_INTCTRL = 1;
    
    sei();
    
    TWI_Init(0x1F);
    TWI_Enable();
    
    puts("Enter Time\r");
    scanf("%8s",t);
    //hh:mm:ss

    TWI_Start(DS3231_ADDR);
    TWI_Write(0b00000000);
    TWI_Write(((t[6]-48)<<4) + ((t[7]-48)&0x0F));
    TWI_Write(((t[3]-48)<<4) + ((t[4]-48)&0x0F));
    TWI_Write(((t[0]-48)<<4) + ((t[1]-48)&0x0F));

    TWI_Stop();

    
    while (1) 
    {
        
        if (trigger)
        {
            TWI_Start(DS3231_ADDR);
            TWI_Write(0b00000000);
            TWI_Start(DS3231_ADDR+1);
            
            TWI_Read(&s,1);
            TWI_Read(&m,1);
            TWI_Read(&h,0);
            
            LED_toggle_level();
            TWI_Stop();
            
            s = (s & 0b00001111) + (s>>4) * 10;
            m = (m & 0b00001111) + (m>>4) * 10;
            h = (h & 0xF) + (h>>4 & 0x3) * 10;
            printf("%d:%d:%d\r\n",h,m,s);
            
            trigger = 0;
        }
    }
}