Olin Lathrop <olin_piclist@EMBEDINC.COM> wrote...

>On the F series parts you can read the program memory
>directly, which allows for totaly different table structures.  These =
kind of
>tables take a few more cycles to access and will use the EECON hardware,=
 but
>store 14 bits of data per program memory location instead of just 8.

Unfortunately, not all the "F" series parts can do this.

I've been using this technique on the 'F877 to look up sine table
entries in a software-driven DDS audio signal generator; it works very
well and doesn't take significantly more cycles than the code for a
retlw-type table lookup routine written for large tables.

However, when I went to migrate this system to an 'F628, I discovered
that the 'F87x series are apparently the only parts (so far) to allow
program memory access through EECON.  On the 'F628, EECON can only
access data EEPROM, so I had to resort to retlw-type tables.

DD

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.