gnupic: Thread: 12F675 EEPROM location

Hi,

I hope to start using the 12F675 shortly (after the parts i have ordered 
arrive)  I am wondering however, what the origin of the EEPROM data 
memory is.  I have not ben able to find reference to it at all in the 
12F675 data sheet or programming spec nor in the PIC midrange manual. 
is it 0x2100 as is the case with the 16F84?

Cheers

John

On Tue, Feb 03, 2004 at 10:27:46AM +1000, John and Anne Duncan wrote:
> Hi,
> 
> I hope to start using the 12F675 shortly (after the parts i have ordered 
> arrive)  I am wondering however, what the origin of the EEPROM data 
> memory is.

It depends...

>  I have not ben able to find reference to it at all in the 
> 12F675 data sheet or programming spec nor in the PIC midrange manual. 

Because it depends...

> is it 0x2100 as is the case with the 16F84?

And finally it depends...

Depends on what you ask? The tacit agreement between the hex file generator
and the programmer for the part. See the EEPROM data space isn't mapped in
the same memory space as the programming memory. Therefore any binding
of the two address spaces is arbitrary. So the answer depends on what the
programmer expects. So take a look in the documentation for the programmer
to determine the answer.

Give that, the answer is most likely still 0x2100. the 12F675 as a 14 bit
part will not have an address space that exceeds 0x2000, so its configuration
memory is still located there. 0x2100 was choosen because it was the first
address space guaranteed not to occupy anything. For example in the 18F
family of parts the space has been moved to 0xF0000 because 0x2100 can be
valid program memory.

Hope this helps,

BAJ

On Mon, Feb 02, 2004 at 11:40:28PM -0500, Byron A Jeff wrote:
> Depends on what you ask? The tacit agreement between the hex file generator
> and the programmer for the part. 

Exactly.  And one trick you can use to find out what this tacit agreement 
was (in case you're blindly using closed source solutions and can't check 
for yourself) is to use the programmer to read from the part, and then 
examine the hex file.

Look for odd sections, like that for 0x2100.

(For quite some time I had an assembler and programmer that used a very
strange location for the config word, so I can understand the idea).

-- 
James Cameron    ####@####.####     http://quozl.netrek.org/