|Re: User programmable ROM module ?|
Message #17 Posted by Diego Diaz on 9 Sept 2003, 6:58 p.m.,
in response to message #1 by Pavel Korensky
Pavel, I'm deeply interested in this issue.
Please take a look at: http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv013.cgi?read=40493.
The full thread is interesting indeed, please read.
I'm still working on the PIC18LF252 approach. Last weekend I finished my (home-made) PIC programmer, and I'm still reading the oversized PIC Data-sheet.
I followed the advice from Vassilis Prevelakis (on the referred thread) and sent a mail to Mr. Ioannidis asking for the code, but I haven't received his reply... yet? So the code for the 18C252 is still a secret for me. May you can try to ask him and perhaps the luck be with you... :-)
On time, the MPS430F14x(1) (wich seem to fit the suitable size for the task) are "huge" 64 pin QPF's... Remember you only have 12mm x 23mm PCB space inside a standard 41 module.
They use 1.8v... 3.6v supply. As far as I've tested, all my 41's (I've got 1 "C" 1 "CV" and 3 "CX") started to show a weird behavior when logic "1" falls below 3.5v, this looks like a very narrow gap (0.1v) for the reliability to fit in.
And MPS430's (please correct me if I'm wrong as I've not yet read the full specs) don't run above 8Mhz.
At 40Mhz a PIC18LF252 powered at 4.2v. draws 10mA typical, wich seems quite reasonable. Should the code handle the task efficiently, lower frequencies (and currents) can be reached. Furthermore, the required 1024 cycles for start-up are not needed if you use EC mode, and keep the oscillator running while PIC is in SLEEP.
So, next step, try to get the existing code (I'm not very confident about that) or develop a brand new one from scratch.
If your're interested mail me.