Olin Lathrop wrote:

> > Another thing (yes, this is my first try with the EEPROM !),
> > I'v seen in the HEX file that each other byte (?) is "00".
> > That is, when I create the data with DE directive, they seems to
> > be either 16-bit values, or there is something "going on"
> > with the addresses in the hex file. *And* the addresses
> > in the HEX file are actualy h'4002' when I expected h'2001'.

> There are two different things going on, depending on which PIC you are
> using.

16F629


> On the 16 family, each program memory address is a 14 bit word.
> Intel HEX files are inherently byte oriented, so microchip uses two
> addresses in the HEX file for each PIC program memory address.  The HEX
> file addresses are therefore double the PIC program memory addresses.

> On the 18 family, each program memory address is an 8 bit byte so these
> map to HEX file addresses directly.  However, the DE directive always
> allocates an entire instruction word for each data byte, so we're back to
> two addresses per EEPROM byte in the HEX file, but for different reasons.
> This is also a pain in the source code because not only are all the EEPROM
> addresses offset by where in the HEX file they decided to map the separate
> EEPROM address space to (PICs actually have 3 completely independent
> address spaces: data RAM, program memory, and EEPROM), but the offsets
> within the EEPROM address range are doubled.  Yes, I think this sucks too.
> EEPROM should really be dealt with natively in the assembler and linker.

Well, I'll try to program my HEX file and write some EEPROM-read-
code and see what it finds on the different EEPROM addresses.

My hex file looks like this (end of it):

:02400E00843FED       [Config setings, right?]
:10420000FF00FC00FA00F700F500F300F000EE00FC
:10421000EC00E900E700E500E200E000DE00DB0082
:10422000D900D700D400D200D000CD00CB00C90007
:10423000C600C400C200BF00BD00BB00B800B6008D
:10424000B400B100AF00AC00AA00A800A500A30014
:10425000A1009E009C009A0097009500930090009A
:104260008E008C00890087008500820080007E001F
:104270007B00790077007400720070006D006B00A5
:024280006900D3
:00000001FF

I supose "4200" in line two, is the EEPROM
address "2100". And I should worry about the
extra "00" between each of my values (which
are "FF", "FC", "FA", "F7" and so on), right ?

Jan-Erik.


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