There is a balance between power and performance. On the high performance side, I have run the Microchip chips on 32 MHz before, never tried the 40 MHz. On the low power side, I got a RV (Recreation vehicle) gateway system current down to about 4mA with the uc wake up every 0.5 seconds. Of course there are other peripherals consuming the power. However the uc from Microchip seems to have a large "start-up" current which I never found on the datasheet. Here is a Story I heard from a TI FAE(Field Support Engineer) about Microchip's Nano-Watt technology: On one of the show, a Microchip guy was demonstrating an orange-cell powered microchip Nano Watt design, and the demo kit was handled to visitors some time. So when the Ti FAE got the demo kits, he unplugged the metal from the orange, then plug it back, and the demo kits stoped. Microchip guy immediately took out a real battery from his pocket, "ignited" the dead unit, then the demo kit is back. Microchip basically explain that the orange or fruit juice battery cannot afford the start-up current a uc required, so they use a real battery to get it started, then use fruit juice-powered cell maintain its continuous running. Funny NYPD ----- Original Message ---- From: Robin Abbott To: Microcontroller discussion list - Public. Sent: Thursday, October 4, 2007 3:32:16 AM Subject: RE: [PIC] Assembly language problem - reading EEPROM - 16F877 And of course many of the newer devices have ultra low power modes using a much reduced oscillator. Robin Abbott Forest Electronics - Home of WIZ-C ANSI C Compiler for PIC's with RAD Front end robin.abbott@fored.co.uk www.fored.co.uk -----Original Message----- From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of Howard Winter Sent: 04 October 2007 10:54 To: Microcontroller discussion list - Public. Subject: Re: [PIC] Assembly language problem - reading EEPROM - 16F877 Jinx, On Thu, 04 Oct 2007 16:10:38 +1200, Jinx wrote: > > I have never completely understood the "DC" portion of the > > specification "dc to 20Mhz". Where could I get an explanation > > of this? ? If it is in a PIC data sheet then I have overlooked it > > Fosc = 0. Obviously anything reliant on Fosc isn't going to happen. > A PIC will run with a very slow, eg RC, clock, although the mA/ MHz > does have a bottom limit. I guess you could arrange such a slow clock > for some single-stepping diagnostic purpose. For example having the > PIC select a large R with a 4066 at a particular point Indeed, or have a potentiometer for R so you can vary the speed as you like - there was a development board published by Everyday Practical Electronics (or one of its predecessors) which did this - I think it was one of John Becker's early designs. Or you could have an external oscillator with a logic gate feeding the clock to the PIC, so that you could just stop it with a logic signal if you wanted, and then step it slowly for debugging, using just a meter or LEDs. You could probably even arrange for the PIC to stop itself like this at a particular point, or have some external logic to detect a condition and stop it when it happens. Much cheaper than a logic analyser... Basically, it's not something you need very often, but having it available when you do is very handy! Cheers, Howard Winter St.Albans, England -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist ____________________________________________________________________________________ Fussy? Opinionated? Impossible to please? Perfect. Join Yahoo!'s user panel and lay it on us. http://surveylink.yahoo.com/gmrs/yahoo_panel_invite.asp?a=7 -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist