EX_EXTEE.C question (3)

[PCM programmer]

Having the hard address of 0xA1 in that line is a mistake that was not spotted.

That line should actually be:

[Arakel]

[Arakel]

So why does this has to be with 1 more?
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Yo! I love learning and technology! I just do not have experience so do not be angry if I ask a stupid question about a detail! From so much to remember sometimes I forget the details in order to remember the big problems!

[PCM programmer]

Either method works. It sets the Read/Write bit to "Read" mode.
That's what is required in that function, at that line of code.

[Ttelmah]

The device address is actually the top 7 bits of the number sent:

0baaaaaaax

The 'x' is a flag for read/write.

Now there are two different ways of expressing I2C device addresses.
Texas use the '7 bit format'. So device numbers 0 to 127 (though 0 to 7 and 127, are reserved), which you then multiply by two, and add the extra bit for read/write.
Most other manufacturers use the 8bit address format, with devices only being allowed to use even addresses, so 0, 2, 4, 6 etc..

Now using 'or' '|' is the standard way in code to set a bit without changing any other bit in the number. It'll work even if (for instance) the number was a signed int8, while '+1', risks problems is there is a wrap. I'd avoid this in more serious code, since at some point you will find yourself setting something unexpected. I'd avoid unwanted by using the addition...
Probably if coding this for a real application, I'd actually use a 'chip number' (0 to 7), and then have the code multiply by 2, and add this to the base address (0xA0, stored as 'FIRST_CHIP'). Then I'd probably code a value of '1' as 'I2C_READ', and or with this for the read operation to make it much more self-documenting.

[Arakel]

Yes, I see, first it initializes the internal counter of the EEPROM to go at address "0", then for random read, without a "stop condition" it gives another "start_condition" and gives a read bit.

I am sorry, sometimes its difficult to orient in the code, it becomes so much, that I just can't accept more information. My mind goes blank, like it or not, not accepting and not transmitting :D.
_________________
Yo! I love learning and technology! I just do not have experience so do not be angry if I ask a stupid question about a detail! From so much to remember sometimes I forget the details in order to remember the big problems!