Understanding & Programming the PIC16C84
(now 16F84A)

A beginners’ tutorial

Jim Brown BSc(Eng), HDipEdAd, GDE (Wits)

RTF --> HTML Translation by: Dan Creagan

HTML cleanup and breakup by: James Newton
 

Contents at a Glance

• Contents
• Introduction
• Introducing the PIC’84
• The Instruction Set
• Interrupts on the ’84
• Timers on the ’84
• Using the EEPROM data memory
• Appendix: Program listings

I'm a beginner at PIC wit the pic16c63 and the tutorial is very useful for me. Thanks, Mario

Questions:

• m.a.metcalfe-02@student.lboro.ac.uk asks: " The current version of MPLAB from Microchip doesnt support the C84. Is there an equivelant chip which i can select from its list? "  Yes the F84
   
• sujith_pic@rediffmail.com asks:

  I am new to PIC programming. Is there any good links from which i can learn the basics of PIC programming in C. I have downloaded MPLAB from microchip. Can you plese guide me where to start from.
   
   

• /techref/microchip/begin.htm

Comments:

• In the beginning, MPLAB is recommended. For those of us without a Windows computer, there are gpsim and gputils.
  • gputils: http://gputils.sourceforge.net/
  • gpsim: http://www.dattalo.com/gnupic/gpsim.html
  • gnupic (a general resource): http://www.gnupic.org/
     
• in 1985 i got my first computer (a commodore 64) at the age of 14. at that age you learn fast and by the time i was 15 i could program in basic and assembly using a machine code monitor. when i reached 16 i realised i was somewhat of a nerd,sold the commodore 64 and took up drinking,smoking ,women and started my apprenticeship as an electrician. by the time i was 23 a ressesion had hit the uk and unemployment was high and lots of people were claiming state benefit including me. during my boredom i realised that i should have carried on with the computing when i was 16 and made a career out of it. pc's were at this point were just begginng to take over from the miriad of different computer companies (whose software only worked on their platform(not suprising they all went bust really apart from mac whole survived somehow))vaguely remembering the basics of of my teenage programming years i searched the second hand pages for a by then outdated commodore 64 which i found and purchased for next to nothing i got a few old books from the library and remastered programming the c64 in no time. i wrote a program in assembly which made a tank sprite (younger people will be be wondering what a sprite is :-) )move around the screen controlled via a joystick. at the time i thought how easy it would be to write a game for the commodore but its an outdated computer and it would not sell so not being able to afford a pc(which then would have been something pathetic like a 386/486 sx 50mhz which is only good for the bin these days)i gave it up. by the time i was 26 i could afford a pc and bought a 120mhz pentium and was completely puzzled by the whole windows operating system which seemed to mask any way of programming the damded thing,the windows learning curve started there. in 2001 at the age of 30 i realised that i had been working as an electrician for 14 years and was still no better off moneywise than i was when i left school at 16 so i started back at college on a 2 year hnc course in electronic engineering (1/3 of a degree)now in 2002 i am very conversant with windows, and also due to my first year hnc,logic/boolean algebra/c programming(borland turbo c 3.0) i have given you possibly too much history before cutting to the chase but its fairly relevent. i recently purchased a 16f84a kit and soldered it together the software that came with the kit was terrible (lights.pic) which came as a .pic file (whatever one of those is)which then had to be converted into a .hex file through some terrible dos program and uploaded to the pic chip via a prog called picall.exe i was completely suprised that it worked at all but it did work...it made 5 led's flash in a binary count.....woopy doo , no programming tutorial or nothing . so i scoured the net for info but everything i came across seemed to be aimed towards intermediate/expert thank the lord i found this site i was on the verge of giving it up and binning the 16f84a
   
  Great site. One thing i found was when i wrote your first example program sample.asm and tried to build it i got a cannot find .hex message when i looked closer 3 lines needed altering H'10' H'15' and H'08' needed changing to 0010h 0015h and 0008h then it worked perfectly. one thing i have noticed whilst trying to find info on how to program the damnded pic is that programming instructions have altered,the c programming instructions which i have recently learnt seem different to the ones listed in examples which seem foriegn to me. and ok i can accept this one since i learnt to program assembly on a system developed 20 years ago, but why replace an easy to understand instruction (opcode) such as lda #ff (load accumulator with hex ff) with movlw 00ffh i originally remeber the x and y registers . did someone suddenly decide to call the accumulator the w register? and sta #$0400 (store accumulator at hex address 0400) seems much easier to me than movwf 0400h,f and why has the command jmp been replaced by the BASIC command goto? well you can look at my comments in a light hearted way and laugh thats why i basically put this message up but any help would be greatly appreciated. i really wish i had carried on at 16 because i would have been on top of things now and been something of an expert but things have developed rapidly and i find that as hard as i try to get a full understanding of things technology seems to be increasing at a faster rate than my learning capabilities can cope with. sound familier to anyone? :-)

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