Post by thread:[PIC]: 8bit Data bus using a PIC16F84A.. is it pos

<sorry, forgot to put a subject.. haaahaahaha.> Hola People, I am looking for a document or website with info on it that will tell me how to hookup an 8 bit data bus with an address bus and control bus using a PIC MCU. Im hoping to use a PIC16F84A to do this with PortA as the address/control bus and port B as the data bus. I would like to ability to control up to 8 devices using the bus by simlpy connecting them to the bus, much the same way as you would with an Device Card in an ISA bus on a 'old school' PC. Any ideas on this would be of great help... Many thanks... -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

On Tue, 29 May 2001, Dylan Hillier wrote: > <sorry, forgot to put a subject.. haaahaahaha.> > don't laugh please, James will be angry... > > Im hoping to use a PIC16F84A to do this with PortA as the address/control > bus and port B as the data bus. > I would like to ability to control up to 8 devices using the bus by simlpy > connecting them to the bus, much the same way as you would with an Device > Card in an ISA bus on a 'old school' PC. > Prototype reserved area for standard PC is 300H...31FH. You need some requirements: -- highZ for data signals -- address decoding pins, I think you can't do a full decode selection only with porta -- WR and RD signals -- no interrupts ? -- ISA bus frequency less than 8MHz ( available in old PC ) or a good software and 40Mhz pic I think there are other pic microcontrollers which will fit better your requirements. Vasile -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

At 01:40 PM 29/05/01 +0300, you wrote: {Quote hidden}>On Tue, 29 May 2001, Dylan Hillier wrote: > >> <sorry, forgot to put a subject.. haaahaahaha.> >> > don't laugh please, James will be angry... > > >> >> Im hoping to use a PIC16F84A to do this with PortA as the address/control >> bus and port B as the data bus. >> I would like to ability to control up to 8 devices using the bus by simlpy >> connecting them to the bus, much the same way as you would with an Device >> Card in an ISA bus on a 'old school' PC. >> > Prototype reserved area for standard PC is 300H...31FH. >You need some requirements: >-- highZ for data signals >-- address decoding pins, I think you can't do a full decode selection > only with porta >-- WR and RD signals >-- no interrupts ? >-- ISA bus frequency less than 8MHz ( available in old PC ) or a good >software and 40Mhz pic > >I think there are other pic microcontrollers which will fit better your >requirements. > >Vasile Yes, I agree. One option would be to use a 17Cxx chip and memory mapped I/O. You could also wait for the Romless 18Cxx chip and do likewise. I don't see that the '84 has enough I/O to do this comfortably. -Jim > >-- >http://www.piclist.com hint: The PICList is archived three different >ways. See http://www.piclist.com/#archives for details. > > > NEWFOUND ELECTRONICS spam_OUTnewfoundTakeThisOuTpipeline.com.au http://www.new-elect.com MPLAB compatible PIC programmers. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

On Tue, 29 May 2001, Andy N1YEW wrote: > sure it has enough pins ya just gotta use a 688 as a address comparator and > an 8 bit bus latch :-) Sorry, I miss the point, why to to with a pic when is much cheaper with one address comparator or a gal16V8 for address decoding and an usual ls245 or ls373. Or if you need more pins, a fast 8255. Using pic16F84 and some other components have nonsens ( my opinion...) See my site: http://www.geocities.com/vsurducan/8255.htm Vasile > > andrew -- i was gonna make a isa programmer but i shelved it > {Original Message removed}

Lack of a programmer for the GAL and lack of board space for the discreets. Also lack of local inventory for either. James Newton (PICList Admin #3) .....jamesnewtonKILLspam@spam@piclist.com 1-619-652-0593 Vasile Surducan wrote on 01-5-29 22:29: On Tue, 29 May 2001, Andy N1YEW wrote: > sure it has enough pins ya just gotta use a 688 as a address comparator and an 8 bit bus latch :-) Sorry, I miss the point, why to to with a pic when is much cheaper with one address comparator or a gal16V8 for address decoding and an usual ls245 or ls373. Or if you need more pins, a fast 8255. Using pic16F84 and some other components have nonsens ( my opinion...) See my site: http://www.geocities.com/vsurducan/8255.htm Vasile > > andrew -- i was gonna make a isa programmer but i shelved it > {Original Message removed}

Guys, My 2 cents worth... It's been my experience that unless you use the Zero Power (TM) GALS, the current demands of the GALs are much too high, ie Several tens of milliamps. A PIC will use just a few mA if that much. So, if your power budget is already being pushed to the limit, I'd stay away from the GALs for this application. Of course, the final decision is up to you. Anyway, that's my thoughts. Regards, Jim On Tue, 05 June 2001, James Newton wrote: {Quote hidden}> > Lack of a programmer for the GAL and lack of board space for the discreets. Also lack of local inventory for either. > > James Newton (PICList Admin #3) > jamesnewtonKILLspampiclist.com > 1-619-652-0593 > > > Vasile Surducan wrote on 01-5-29 22:29: > > On Tue, 29 May 2001, Andy N1YEW wrote: > > > sure it has enough pins ya just gotta use a 688 as a address comparator and an 8 bit bus latch :-) > > Sorry, I miss the point, why to to with a pic when is much cheaper with one address comparator or a gal16V8 for address decoding and an usual ls245 or ls373. Or if you need more pins, a fast 8255. Using pic16F84 and some other components have nonsens ( my opinion...) See my site: > http://www.geocities.com/vsurducan/8255.htm Vasile > > > > > > > andrew -- i was gonna make a isa programmer but i shelved it > > {Original Message removed}