Beginners checklist for PIC Microcontrollers

1. PICList: Subscribe to the PICList http://www.piclist.com. Don't post, just read for a while.
2. PIC: Select a chip and buy one.
   • The simplest chip to program, find code for, learn on is the 16F84,
   • More bang for the buck is the 16F877 and it is mostly code compatible with the 'F84.
   • The most bang for the buck is the 18F series chips and they have many new and advanced features.
3. Static - don't touch the pins without grounding yourself.
4. Programmer Find a programmer that supports your chip.
   • NOPPP is the simplest for the F84 using a PC parallel port (8 resistors, 2 caps, 2 diodes and a transistor and a 13v power source) with software for most OSs,
   • Tony Nixons ASCII programmer is the simplest for the F84 using a serial port (4 resistors, 4 diodes (1 zenor), 2 caps, a NAND gate and a 13v power source). Free software for DOS or write your own (It is very simple). (cached 200003071344)
   • http://www.voti.nl/wloader/index.html Wloader
   • Or you can program an '877 with a stripped down Tait (basically a cable) under Linux.

   (The exhaustive list of all known programmers is at /techref/microchip/devprogs.htm )

5. DO NOT ENABLE CODE PROTECTION! No, it can't be undone. You will have to replace the chip. Read the documentation on your programmer to figure out how to avoid this.
6. Read Goto http://www.microchip.com find, download and read the datasheet for your chip from cover to cover. Read  Jim's introduction to the PIC, the PIC FAQ and ask questions on the PICList if you don't understand something. If your brain is completely fried at this point, don't worry, lots of top-notch engineers have been also. Here are some other ideas:

   • Intros and Tutorials,

     • Understanding & Programming the PIC16C84 by Jim Browns (also at: http://talkingelectronics.com/html/PIC-for-Beginners.html) is the classic intro to the classic PIC16C84. The chip is still available as the 16F84A and the tutorial is still quite valid although it refers to figures in an older version of the Microchip datasheets cached here: 30445B.PDF.
     • CHEAPIC by Stan Ockers [ockers at anl.gov] getting started and some nice projects.
     • The PIC Source Book explains PIC programming in terms of the BASIC Stamp
     • A Beginner's simple Bike Computer project by Fred Maher includes PIC programming, making PCB's circuit design, everything.
     • http://www.voti.nl/swp/index_1.html Starting with PICmicro controllers (C) 2002 Wouter van Ooijen
     • http://amqrp.org/elmer160/lessons/  "PIC Elmer 160 Course Lessons" by John McDonough, WB8RCR is a *very* detailed "click here, press that button" introduction. Gives step-by-step instructions, with screenshots, for downloading and using MPLAB, programming the PIC, single-step debugging, I/O, and subroutines.
     • http://homepage.ntlworld.com/matthew.rowe/micros/dosgear.htm A nice startup page with a (frighteningly) simple programer, DOS software and a sample program
     • http://www.cq-tv.com/articles/picprog.htm Brian Kellys brief introduction
     • http://www.dhmicro.com/prod_fedc.html is a good downloadable beginners' tutorial that is PIC C language specific. As a C newcomer I found this one the most user-friendly and encouraging source.
     • http://www.interq.or.jp/japan/se-inoue/e_pic.htm (cached  20010731113152) If you can get past the poor English, this is a nice site. Does anybody have the time or desire to help him out with his English translations?
   • Books: there are a lot of good books about the PIC
   • Courses: some universities offer courses in embedded design.
   • Starting Projects: http://www.piclist.com/projects
7. Language: Select a development language. Many years ago everyone used assembly language because there was no alternative. A few years ago many people used assembly language because the alternatives were expensive. Now there are lots of alternatives, many of them free. See development language.
8. Start with very simple code like a LED coming on when a switch is pressed, and build from this once it is working.
   • CHEAPIC - BINCNT Program
   • CHEAPIC - SWCNT Program
   • The PIC Source Book - toggle
   • The PIC Source Book - button
   • Flash a LED from an 16F877
9. Don't Float: Tie the switch pin Hi or Lo with a ~10K resistor or use internal pullups to avoid floating inputs when the switch is open. In general, do something with unused pins don't just leave them floating
10. TRIS - make sure they are set properly for in/out pins.
11. Debounce the switches to avoid false switch states.
12. RA4 on a 16F84 is "open collector" - it can pull to ground but will not pull up to V^cc. You can still use it to drive LEDs by hanging the LED & resistor between RA4 and +5V supply. (anode to +5V) This means that the logic is now inverted; 1 = off and 0 = on
13. Diasble WDT if not needed
14. Check MCLR is connected to V^cc
15. Connect ALL V^cc and V^dd pins. Not just one of each.
16. Make sure Osc fuses are set for your type of oscillator, crystal (XT), RC (RC), resonator (HS).  etc
17. Sample code for most common applications (including serial io, LCD interfaceing, keyboards, the internet, etc...) are available at the PICList FAQ http://www.piclist.com/faq
18. When your code doesn't work:
    1. Set the entire program aside, find a way to seperate just a small, but functional part of it and get that part working. Then, slowly add in the rest of the code from the original program, testing and debugging each addition, untill you have the entire program working
    2. Comment each and every line of the code with what you think it is doing, and then check the datasheet against your comments.
    3. Post the commented code to the piclist with a subject line of "[PIC]: What am I missing in this code?"
19. For good ideas on second and third projects, see: http://www.piclist.com/projects. Good starting projects with lasting value.

Still not getting anything to work? Try

• PIC Tips, Tricks, Traps Gens and Snares
• if you're useing MPLab, check MPLAB Bugs
• General Electronic Tips, Tricks, Traps Gens and Snares

If you are going to do this for a living, see the begining engineers checklist

Questions:

• visn@spam@ at KILLspamwbs.co.za asks:

  Nearly the end of 2007 and I want to get back into PICS
  16F628 @ 1 , 16F88 @ 1.9(*price of 628) 16F873 @ 2.1 , 16F877 @ 2.9 and the USB 18F4550 @ 3x.
  Is the 628 still a drop in for the 84, or is the 88 a better bet to invest a few?.
  18F4550 is tempting, but I can't choose between that , the 877 , and the AVR MEGA8-16 @ 0.8 (price of 628).
  And my f84 programmer was dos based and is in pieces.
  I want to know , though, the best drop in for the F84- F628?-or F88?

  James Newton replies: I think it's a toss up and depends more on what sort of development you want to do in the future. If USB is important, go with that, and so on.+

  +

• +
• tommowas@spam@ at KILLspamhotmail.com - hi ppl. i have a problem with understanding the goto command.. i have encountered source code which goes to a subroutine and then that subroutine has a 'return' or 'retlw' in it. does goto work the same way as call? could someone please explain its difference. regards. sorry about the double post. James Newton replies: See the instruction list section of the datasheet for the processor you are using for the exact action of the goto, call, return, and retlw commands.+ +
• madyg@spam@ at KILLspamexcite.com asks: " the Pic can see a "1" or a "0" however how can a Pic "see" the middle position of a 3 state dip sw?" James Newton replies: Assuming there is a 1k resistor between the switch and the pin, set the pin as an output, pull it low then immediatly switch back to an input and read the value. If it stayed low, repeat the process but pull it high instead. If it stays where you put it, the switch is in the middle.

  This is making use of the pins own internal capacitance and would be more reliable with a small cap between the pin and ground. At that point you basically have an RC circuit such as is used in a sigma-delta A to D converter or the POT command used in the BASIC STAMP.+

  +

See also:

• http://www.gooligum.com.au/tutorials.html Some people have found the Gooligum tutorials useful.+
• http://homepages.paradise.net.nz/dkwinter/pic.htm A nice tutorial on how to make an LED flash with the PIC16F84 - Great for the absolute newbie :D
• http://www.al-williams.com/pictutor A tutorial aimed at the 16F84 or APP-II (a preprogrammed 16F873). Has a nice Java "walkthrough" of creating an MPLAB project.
• Hi there is group for Embedded Basic.
  http://groups.yahoo.com/group/Embedded_Basic 

Archive:

• PICList post "- Very Newbie - What Do I Do Now?" +
• PICList post "- Very Newbie -Why won't this program compile?. " +
• PICList post "- Very Newbie - Progress!" +
• PICList post "Interrupt and bit shifting" A good project with timers and an LED on a '628 +
• PICList post "code that causes crash..." An EXCELLENT job by Myke of helping a new PIC user debug some code. +

Comments:

• Super.. this site has all info required by a PIC beginner...hatz off to these guys :-)++
• dave j lagzdin of davesaudio These were the best tutorials for me, didn't notice them on the list:
  http://www.winpicprog.co.uk/pic_tutorial1.htm {ed: see also: http://www.winpicprog.co.uk/pic_tutorial.htm }
  http://www.mstracey.btinternet.co.uk/pictutorial/picmain.htm
• +After battling with a 18f452 for ages, trying to get it to run at 40 mhz using the PLL_HS with a 10 mhz resinator, all I could get it to do was oscilate at 10 mhz. The solution is to add a 4m7 resistor across the osc1 and osc2 pins. Works like a charm!
  .Barney.
  +
• ned@spam@ at KILLspambike-nomad.com I'd question whether the "most bang for the buck" is really the 16F877 any more. Looking at Digikey's qty 1 price: 16F877-20I/P $9.88 18F452I/P $9.38 The 18F part is twice as fast, and has a much nicer instruction set, more flash, much more ram, etc... +

  Good Point. I've updated the page to reflect that. I'm still a bit concerned that the code changes in the 18F series may prevent beninners from makeing use of the wealth of existing code for the smaller cores.

See:

• /techref/microchip/16f877cpde.htm Can't re-program chip after code protecting the data eeprom+
• Diede A. van Abs Says: " link to bubblesoftonline.com is dead. (also tried in separate browser window, site is gone) " James Newton replies: Use http://web.archive.org/*/http://www.bubblesoftonline.com. +

  replies: The archive is also inaccessable - its tells you: "We're sorry, access to http://www.bubblesoftonline.com has been blocked by the site owner via robots.txt"+

  You might try http://web.archive.org/*/http://www.picnpoke.com

Bert van Dam Says:

http://members.home.nl/b.vandam/lonely/index.html Has lot's of information including a 'Getting started'and 'Tutorial' section for beginners using JAL as PIC language. Also contains may pages for intermediate and experts.

  .