AVR Freaks

Hello.

Finally back to my TWI thing.

I've been looking to the code in those 2 files.

I have some questions because I'm not sure if things are the way I'm thinking they are!

I'll go through each code regarding each question.

In the following code:

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))
				/*wait*/;
		}
		else{
			while (!(TWI0_MSTATUS & TWI_WIF_bm))
				/*wait*/;
		}
		return TWI0.MSTATUS;
	}
	else
		return TWI0.MSTATUS;
}

First question is why there is this TWI_Start() function and then one other for the Read operation and another for the write operation? I had created only the TWI_Init() and then the TWI_Read() functions. Is this "Start" function mandatory?

Then, I don't understand why there is an ACK signal being sent if the BUSSTATE is different from BUSY... Can you please explain me why?

Then, I don't understand why there is this IF with "addr & 1 ". What is the purpose of this? If this is to set a READ/WRITE operation, then, why are there specific functions for the same Read/Write operations?

Also, RIF and WIF, according to the User Manual, says that these bits are set when a Read or Write operations are successfully completed. But this function has no code to read or write anything from/for the BUS. So why is this code inside this function? Or am I getting all wrong?

Yes, you have already suggested to study Fleury's code and try to start from there, but at this point, I want to try the other suggested code! I was just trying to understand how that code works so that I can use it properly!

Just temperature values. The first byte that is read, should not be 0 either!

Line 108 of the code. It's in TWI_Read() function! Address is 0x18!

The Slave device is a temperature sensor MCP9808.