Post by thread:emulation at 3 volts

Last week I asked the question if anybody knew of an add on signal level translator for the Picmaster emulator. I didn't receive any replies which prompts me to ask "Does anybody run on 3 volts?" If you do run on 3 volts how do you emulate during debug? I understand that if the total system could be ran at 5 volts then it wouldn't require a translation, one would turn up the voltage, emulate till "all" bugs are gone, then set the voltage back down to 3 and hope the additional prop delays don't cause any problems. I cann't do that because of the analog circuits in the system. Maybe the questions to ask are" "Does anybody know of an emulator that runs at 3/5 volts ?" "Is there a market for an emulator signal level translator?" "Am I the first in the history of mankind to face this problem?" Harris Corporation does not make this type of equipment. regards Jerry English

> Last week I asked the question if anybody knew of an add on signal level > translator for the Picmaster emulator. I didn't receive any replies which > prompts me to ask "Does anybody run on 3 volts?" If you do run on 3 > volts how do you emulate during debug? I understand that if the total > system could be ran at 5 volts then it wouldn't require a translation, > one would turn up the voltage, emulate till "all" bugs are gone, then > set the voltage back down to 3 and hope the additional prop delays don't > cause any problems. > I cann't do that because of the analog circuits in the system. > Maybe the questions to ask are" > "Does anybody know of an emulator that runs at 3/5 volts ?" > "Is there a market for an emulator signal level translator?" > "Am I the first in the history of mankind to face this problem?" Well, one approach which may sometimes work is to run the CPU off +5, every- thing else off +3, and put resistors on the PIC outputs to avoid excessively overdriving the stuff that expects +3. If you're operating in the digital domain, this technique should work (if you're careful that the +3 rail does not bounce all over the place) even if you have analog stuff in the circuit. If you're relying on the PIC's inputs or outputs to have certain analog be- haviors (e.g. switching at some magic threshhold) then you may be out of luck (even when running off +5, though, emulators are often dicey on such things anyway).

Jerry English <spam_OUTPICLISTTakeThisOuTMITVMA.MIT.EDU> wrote: > If you do run on 3 volts how do you emulate during debug? I > understand that if the total system could be ran at 5 volts then it > wouldn't require a translation, one would turn up the voltage, > emulate till "all" bugs are gone, then set the voltage back down to > 3 and hope the additional prop delays don't cause any problems. Jerry: Yeah, that's what I do. It's not perfect, as you say, but it works for most applications. > I can't do that because of the analog circuits in the system. Damn. > Does anybody know of an emulator that runs at 3/5 volts? All the PIC emulators of which I'm aware use Microchip's bondout emulator chips, which don't work real well below 5 volts. > Is there a market for an emulator signal level translator? I can't speak for the whole marketplace, but if it were priced right and let me easily configure which pins were translated (and in which directions), I'd buy one. > Am I the first in the history of mankind to face this problem? No, but you're the first on the PICLIST (as far as I know) to propose the level-shifter box as a solution. -Andy === Andrew Warren - .....fastfwdKILLspam@spam@ix.netcom.com === === Fast Forward Engineering - Vista, California === === === === Custodian of the PICLIST Fund -- For more info, see: === === http://www.geocities.com/SiliconValley/2499/fund.html ===

At 05:01 PM 1/13/97 -0800, you wrote: > All the PIC emulators of which I'm aware use Microchip's bondout > emulator chips, which don't work real well below 5 volts. ^^^^^^^^^^^^^^^^^^^ Sounds like official Microchip terminology > >> Is there a market for an emulator signal level translator? > > I can't speak for the whole marketplace, but if it were priced > right and let me easily configure which pins were translated > (and in which directions), I'd buy one. I'd be cautious, most people still use DIP packages. 3v might be a pretty small user base.

--- snip --- >system could be ran at 5 volts then it wouldn't require a translation, >one would turn up the voltage, emulate till "all" bugs are gone, then >set the voltage back down to 3 and hope the additional prop delays don't >cause any problems. >I cann't do that because of the analog circuits in the system. >Maybe the questions to ask are" > "Does anybody know of an emulator that runs at 3/5 volts ?" > "Is there a market for an emulator signal level translator?" --- snip --- That's what I do too. And yes a 3v translator would have come in handy a few months ago. Maybe for your application you won't need to translate all the lines. ----------------------------------------------------------------------------- bryanKILLspamwllink.com Wireless Link Corporation -----------------------------------------------------------------------------