Post by thread:Another stupid question

What's the difference between Microchip xxCxx and xxCRxx parts? AFAIK CR version is ROM based and C version is EPROM based... but.. what exactly does it mean?? I need a different programmer?? -- - *Alex* - (spam_OUTazummoTakeThisOuTita.flashnet.it)

Alessandro Zummo <.....PICLISTKILLspam@spam@MITVMA.MIT.EDU> wrote: > What's the difference between Microchip xxCxx and xxCRxx parts? > AFAIK CR version is ROM based and C version is EPROM based... Correct, Alex. > but.. what exactly does it mean?? I need a different programmer?? Uh... No, not exactly. Because the CR parts are ROM-based, you CAN'T program them yourself; they're "programmed" by the Microchip factory. -Andy === Andrew Warren - fastfwdKILLspamix.netcom.com === Fast Forward Engineering - Vista, California === http://www.geocities.com/SiliconValley/2499

Il 14-Dic-97, Andrew Warren scrisse: >> but.. what exactly does it mean?? I need a different programmer?? > Uh... No, not exactly. Because the CR parts are ROM-based, you > CAN'T program them yourself; they're "programmed" by the > Microchip factory. thx.. Ok.. and what about F parts? Flash? Some Pics are selled woth a preprogrammed osc type... what happen if, while programming, i'll change the osc bits? Thanks, - *Alex* - (.....azummoKILLspam.....ita.flashnet.it)

Il 14-Dic-97, Andrew Warren scrisse: >> but.. what exactly does it mean?? I need a different programmer?? > Uh... No, not exactly. Because the CR parts are ROM-based, you > CAN'T program them yourself; they're "programmed" by the > Microchip factory. thx.. Ok.. and what about F parts? Flash? Some Pics are selled woth a preprogrammed osc type... what happen if, while programming, i'll change the osc bits? Thanks, - *Alex* - (EraseMEazummospam_OUTTakeThisOuTita.flashnet.it)

Alessandro Zummo <PICLISTspam_OUTMITVMA.MIT.EDU> wrote: > Ok.. and what about F parts? Flash? Yeah, sorta... The 16F84 and 16C84 use EXACTLY the same memory technology; Microchip (and other manufacturers who use the same technology, like Atmel) just decided to call it "Flash" instead of "EEPROM". > Some Pics are selled woth a preprogrammed osc type... what happen > if, while programming, i'll change the osc bits? Very few, if any, are sold that way anymore. If you do have a PIC with a pre-programmed oscillator type, it'll PROBABLY work if you reprogram it, but Microchip won't guarantee its operation. Note that if the oscillator's set to XT or LP, it can only be reprogrammed to HS, and if it's set to HS, it can't be reprogrammed at all... The only oscillator type that can be reprogrammed to all of the others is RC. -Andy === Andrew Warren - @spam@fastfwdKILLspamix.netcom.com === Fast Forward Engineering - Vista, California === http://www.geocities.com/SiliconValley/2499

On Sun, 14 Dec 1997 19:46:45 +0100 Alessandro Zummo <KILLspamazummoKILLspamITA.FLASHNET.IT> writes: > What's the difference between Microchip xxCxx and xxCRxx parts? > > AFAIK CR version is ROM based and C version is EPROM based... > > but.. what exactly does it mean?? I need a different programmer?? With the "R" version, you can't program the program memory area at all. It's a mask ROM, which means the program is printed right onto the chip during manufacture as a pattern of links and opens. You'd have to submit a hex file to Microchip and have them make the chips for you with the program already masked in. This could be slightly less expensive if tens of thousands of identically- programmed devices are used. A standard programmer should be able to read the CR chips (and modify the *data* EEPROM in "83" and "84" chips) if the code protect is not set.

> Note that if the oscillator's set to XT or LP, it can only be > reprogrammed to HS, and if it's set to HS, it can't be > reprogrammed at all... The only oscillator type that can be > reprogrammed to all of the others is RC. Slight correction: HS mode can be left as-is or programmed to LP. XT mode can be left as-is or programmed to LP. LP mode cannot be reprogrammed. Also note: A device programmed for HS mode will work fine with a 4MHz crystal; it will use more current than an XT-mode programmed device but may start more reli- ably. Most programmeers will refuse to program an HS-fused device if the fuse settings in the hex file specify XT (change the hex file to HS). While any device may be programmed for LP mode, only the LC devices are rated for the lowest voltages that LP mode makes possible. Some devices, such as the 16C84, have fairly high minimum voltage specs even at 32KHz (except in LC versions).

John Payson <RemoveMEPICLISTTakeThisOuTMITVMA.MIT.EDU> wrote: > Slight correction: > > HS mode can be left as-is or programmed to LP. XT mode can be left > as-is or programmed to LP. LP mode cannot be reprogrammed. Thanks, John. -Andy === Andrew Warren - spamBeGonefastfwdspamBeGoneix.netcom.com === Fast Forward Engineering - Vista, California === http://www.geocities.com/SiliconValley/2499

Il 14-Dic-97, Andrew Warren scrisse: >> Some Pics are selled woth a preprogrammed osc type... what happen >> if, while programming, i'll change the osc bits? > Very few, if any, are sold that way anymore. > If you do have a PIC with a pre-programmed oscillator type, > it'll PROBABLY work if you reprogram it, but Microchip won't > guarantee its operation. since they were tested for that osc type? What about JW parts.. are they available of all pic models? -- - *Alex* - (TakeThisOuTazummoEraseMEspam_OUTita.flashnet.it)

The Rom based parts are available from the factory with your program in it. You can not program them in the field. They make sense if your code is solid and you have high volume to reap the savings. There is an NRE associated so the need for a high volume to save money is there. I have a couple of clients that have Rom based 54 designs in high volume and have saved a lot of money but if a problem is found they panic because they would need to eat the chips made so far if a program change is needed. At 07:46 PM 12/14/97 +0100, you wrote: {Quote hidden}> What's the difference between Microchip xxCxx and xxCRxx parts? > > AFAIK CR version is ROM based and C version is EPROM based... > > but.. what exactly does it mean?? I need a different programmer?? >-- > > - *Alex* - > > (RemoveMEazummoTakeThisOuTita.flashnet.it) > > Larry G. Nelson Sr. L.NelsonEraseME.....ieee.org http://www.ultranet.com/~nr

Alessandro Zummo <EraseMEPICLISTMITVMA.MIT.EDU> wrote: > > If you do have a PIC with a pre-programmed oscillator type, > > it'll PROBABLY work if you reprogram it, but Microchip won't > > guarantee its operation. > > since they were tested for that osc type? Correct. > What about JW parts.. are they available of all pic models? JW parts, which can be programmed to any oscillator type, are available for all but the EEPROM-based PICs (16C8x/F8x, etc.). -Andy === Andrew Warren - RemoveMEfastfwdEraseMEEraseMEix.netcom.com === Fast Forward Engineering - Vista, California === http://www.geocities.com/SiliconValley/2499