Post by thread:Diffrence between C84 & C71?

Hi PIcers? I wrote a piece of code which runs fine on a 16C84 and then i tried it on a 16C71 without success.. I don't really understand why, 'cause the two uCs seem to be identical with the exception of course of the DA converter of the C71 and the EEPROM of the 16C84. Since my code doesn't use any DA or EEPROM i believe it should run on both UC without modifications. Right? Anybody knows what might be wrong? Tips: Thesame source was recompiled for each uC. I'm testing the 2 chips on the same board that works well. (the 16C71 actually runs). The program doesn't even use timers and watchdogs and such things. Thanx Spiros Papageorgiou Email: spam_OUTmc89114TakeThisOuTcentral.ntua.gr

Papageorgiou Spiros wrote: {Quote hidden}> > Hi PIcers? > > I wrote a piece of code which runs fine on a 16C84 and then i tried it > on a 16C71 without success.. I don't really understand why, 'cause > the two uCs seem to be identical with the exception of course of the > DA converter of the C71 and the EEPROM of the 16C84. > Since my code doesn't use any DA or EEPROM i believe it should run on > both UC without modifications. Right? > Anybody knows what might be wrong? > > Tips: Thesame source was recompiled for each uC. > I'm testing the 2 chips on the same board that works well. (the 16C71 actually > runs). > The program doesn't even use timers and watchdogs and such things. > > Thanx > Spiros Papageorgiou > Email: > .....mc89114KILLspam@spam@central.ntua.gr Hi When you want to run code written for the C84 or C61 on a C71, you must add a line to your program (at the begining) in which you must set the 3 least significative bytes of the register ADCON1. If not, some inputs (RA0-3) will be configured as analog input after the reset and they do not work as you expected (as digital inputs). Bye. --|----------------------------------------------------------------|-- --| |-- --| Fernando G. Martin EMAIL fgmartinKILLspamstarnet.net.ar |-- --| |-- --|----------------------------------------------------------------|--

In message <.....199608042108.AAA09884KILLspam.....central.ntua.gr> EraseMEPICLISTspam_OUTTakeThisOuTMITVMA.MIT.EDU writes: > Hi PIcers? > > I wrote a piece of code which runs fine on a 16C84 and then i tried it > on a 16C71 without success.. I don't really understand why, 'cause > the two uCs seem to be identical with the exception of course of the > DA converter of the C71 and the EEPROM of the 16C84. > Since my code doesn't use any DA or EEPROM i believe it should run on > both UC without modifications. Right? Right. I generally do my initial development on a C84 before moving over to a C61 or C71 (which ever the final design will use). Mike

Papageorgiou Spiros <mc89114spam_OUTCENTRAL.NTUA.GR> wrote: > I wrote a piece of code which runs fine on a 16C84 and then i tried it > on a 16C71 without success.. I don't really understand why, 'cause > the two uCs seem to be identical with the exception of course of the > DA converter of the C71 and the EEPROM of the 16C84. On the 16C71, you have to explicitly turn the A/D converter off. Why on earth didn't Microchip make this the default? Cheers, Eric

> Papageorgiou Spiros <@spam@mc89114KILLspamCENTRAL.NTUA.GR> wrote: > > I wrote a piece of code which runs fine on a 16C84 and then i tried it > > on a 16C71 without success.. I don't really understand why, 'cause > > the two uCs seem to be identical with the exception of course of the > > DA converter of the C71 and the EEPROM of the 16C84. > > On the 16C71, you have to explicitly turn the A/D converter off. Why > on earth didn't Microchip make this the default? Most likely they disabled the digital inputs on reset to avoid excess current draw that might otherwise result from having the port pins at an indistinct logic level (unlike digital inputs which might float but would usually tend one way or the other, A/D inputs in normal usage would probably tend to be somewhere in the middle of the sacle). The rationale is reasonably sound; it would have been nicer to have a little more transparent implementation, however.