Pick A PIC Project
Colin Mitchell
Colin Mitchell
October 12, 2010
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Table Of Contents

  • PIC Programmer MkV
  • Instruction Set for PIC16F628
  • PIC16F628 PDF Data Sheet
  • BlankF628.asm
  • PIC16F628A.inc

See more projects using micros:

  • P2(100 Helpful Hints)
  • P3 The XOR Trick

If you want to get into the next generation of “project-design,” you need to look into the magic world of a MICRO.
A micro can simplify your project, reduce its size, increase its capability and reduce the cost.
But best of all, it can be centered around a software program that can be hidden from prying eye and this will make your project unable to be copied.
Talking Electronics has produced a range of projects using a MICRO and this article will get you into designing your own project at the lowest cost.There are a number of microcontrollers on the market and various paths you can follow to produce a microcontroller project - at least 3 different manufacturers and more than 3 paths are available.
Ours is just one of these options and in our opinion it is the cheapest and simplest way to get into microcontroller programming.
We have chosen the PIC micro, by MicroChip as it has a huge following on the web with a large range of projects and support groups.
In addition we have chosen hand-programming using a template to get you started. Our method produces lines of code where each line is an instruction. This is the simplest way a PIC program is produced and you produce it by hand.
The instructions are fairly easy to understand as they consist of the first letter of words of a sentence, such as btfss (bit test file and skip if set) and these are called mnemonics.
There are only (about) 35 instructions and these cover the entire capability of the microcontroller.
This is the simplest and easiest way to write a program and is aligned to the early days of programming where it was called “Machine Code.”
This is the “Lowest Level Language” as the instructions are directly understood by the micro. Any other language is a “higher level language” as each instruction is usually more powerful but much harder to add to the program. You need to learn these languages and how to write them in a program (how to structure each line) as they use symbols such as: ”{, }, [, ], <<, >>” to produce code such as:

void waitsync(void)
  re: while (RX)
if(errorbyte > MAXERR) { errmark=1; return;};

Our approach avoids a lot of complexity and frustration. It only involves 35 instructions.
We have made programming even easier by providing a number of complete projects as well as “sub-routines” that can be copied and pasted into your program.
On top of this we have provided a LIBRARY OF TERMS to help you understand all the terms. And to simplify things we have concentrated on two PIC chips. An 8 pin and an 18 pin chip. The 8 pin chip can be either PIC12F629 or PIC12F675 and the 18 pin chip is PIC16F628 or PIC16F675.
Even though these chips are the simplest in the range, do not under-estimate their capability.
The PIC16F628 can easily replace 20 individual logic chips and produce a project with amazing capability. We have produced a Tic Tac Toe game that always wins (or draws) and a Dialing Alarm-2 that produces DTMF tones, a Hee Haw sound and a feature that opens up a microphone to let you listen to the target zone.
By using our suggestions, you can use the chip to its fullest and create a more-complex program than any other method. You don’t have to learn any other “language” or get involved with any “developmental tools” (some of these are very frustrating to use).
We have also used very simple “programming techniques” in that our “lines of code” are very easy to follow and clearly explained. Some developers use “very clever” instructions that take “hours to understand” and this leaves you in a state of frustration. We do it “the simple way” and you feel bolstered after every project you complete.
Of course you cannot produce an “all talking, all dancing” project with these tiny micros but our aim is to get you started.
If you can visualise the capabilities of a 5 chip project; multiply this by 10 and you have the possibilities of what you are about to encounter. This may seem surprising but as your program gets larger, you can use some of your pre-written sub-routines and this makes it more-powerful and the last-few lines of code can achieve enormous capabilities.
Producing a microcontroller design is often cheaper than using lots of discrete chips; plus the board is smaller. But most important, the program can be “locked away” from prying eyes and can be marketed.
Now is the time to think of some ideas. In most cases they will be “do-able.” And we will show you the way.

Below is a list of projects we have developed for the two chips as well as PIC Programmer MkV, for those with a desk-top computer or tower and PICkit-2 Burner for those with a lap-top computer.
First you have to decide on the programmer. It will depend on the “port” you have on your computer.

Look at your computer or “tower” or lap-top. Does it have a serial port:

Serial Port

You need to buy PIC Programmer MkV kit

a USB port:

USB Port

You need to buy PICkit-2 Burner kit.

Once you have decided on a programmer, you will need to buy the kit and assemble it.
Connect it to your computer and go to the projects below. Start with: World’s Simplest Program. It uses a PIC12F629 and has only 4 instructions to blink a LED. It shows how the Watch-Dog Timer resets the chip every 150mS. It’s not a normal type of program but it tests the micro, the programmer and the circuit you have constructed.
Then alter one or two of the instructions and see what happens. If you can do this, you are ready to start.
The projects are divided into two groups: PIC12F629 (8 pin) or PIC16F628 (18 pin).
Both micros use the same instruction-set (only some small differences) and both are identical when it comes to learning how they operate. The only difference is the 8 pin micro has 5 in/out lines and 1 input-only line. The 18 pin micro has 15 outputs (plus one input-only line).


The following list of data sheets, projects and “help” articles is like a course. It covers everything you need to know about producing a PIC microcontroller project.
Everything can be accessed via links on Talking Electronics website and is also available on CD from Talking Electronics for $10.00 posted to anywhere in the world.
This is the lowest-cost course ANYWHERE on the web and it starts at less than $50.00 for a PIC programmer and project. You also get a CD containing all the necessary information including instructions for all the kits.
Even though our approach is the simplest way to get into PIC programming, you may have a question and it can be answered by contacting Colin Mitchell or going to a forum, where microcontroller questions will be answered 24 hours a day! One of the forums is: http://www.electro-tech-online.com/


There are a number of other micros on the market and many of them offer a similar range, price and set of features as the PIC.
We have chosen the PIC because of the enormous amount of help and number of projects on the web.
At this point in time, no-one has written an article to say any other processor is markedly better than a PIC and so you are not being steered down a “dead end.”
One of the other manufacturers ceased to produce their smallest micro and that’s why their “attiny” range was not chosen. We were just about to promote the attiny12 series when it ceased to be manufactured. Luckily, the equivalent PIC chip is cheaper.


A set of experiments using the LED Fx PC board. The course contains a folder with the file for writing your program (NotePad2), converting your .asm to .hex (MPASM) and for burning a PIC micro (ICPROG).
You will need a fully built LED Fx, and Pic Programmer MkV
If you have a USB port, you will need PIC-2 USB Burner and PICkit2 software. Here are the data sheets, projects and “help” articles:


Software for PIC Programmer MkV


  • Pic Programmer MkV Simple PIC programmer - uses just 12 Parts - for serial port
  • PIC-2 USB Burner for lap-top USB port
  • World’s Simplest Program for a PIC12F629. It uses only 8 instructions and blinks a LED. It shows how the Watch-Dog Timer resets the chip every 18mS to 2400mS if not cleared.Kit contains PC board, 6 pin to 5 pin adapter, 8pin socket, chip, LED, resistor and pins to create a development board for burning 8 pin PIC chips.



Audio CRO uses PIC12F675 to produce a simple audio CRO via a spinning PCB on the shaft of a motor. A good mechanical as well as electronic project.


  • Dial Alarm-2 Dials 2 phone numbers via DTMF and produces a Hee Haw Sound. Has a in-built microphone to listen to the target zone. Uses a PIC16F628
  • PIC Lick-1 A development board for the PIC16F628
  • Simon 4 buttons are used to repeat a sequence of Lights and sounds. Uses a PIC16F628
  • Stroop Game A very interesting Psychological game named after the doctor who introduced the test. Uses a PIC16F628
  • Tic Tac Toe A challenging game where the computer wins or draws. Uses a PIC16F628.
  • 15x7 Display using a PIC16F628
  • 2 Digit Up/Down Counter 5 different designs. Uses PIC12F629 or PIC16F628 chips.
  • 12 Digit Display A 12 Digit calculator display is used to produce a running sign and other effects. Uses a PIC16F628


Here is some helpful facts on the PIC12F629 and PIC16F628 micros:
The PIC12F629 has 1024 locations for your program. This is 4 pages and is commonly called 1k of memory. A page has 256 locations (0FFh locations). Page0 consists of locations 00h to 0FFh. Page1 consists of locations 100h to 1FFh. Page2 consists of locations 200h to 2FFh. Page3 300h to 3FFh.
The PIC16F628 has 2048 locations for your program. This is 8 pages. This is 2k of memory for your program.
Goto and Call instructions access the whole of memory.
A table can only be 0FFh locations long and it must not go over a border. For instance it can be from location 006h to 0FFh or 100h to 1FFh or 300h to 3FEh (for the PIC12F629) - the last location stores the oscillator calibration-bit and cannot be used for your program.
The microcontroller has different areas for storing different pieces of data. There are 4 main areas that contain files or registers to store these values.
The first and largest area is 1k or 2k and stores your program. This is called the CODE AREA or PROGRAMMING AREA or CODE SPACE and is in the CORE AREA of the chip. This area is also in “BANK 0” of the micro but is normally referred to as the CORE AREA.
The second and third areas contain Special Function Registers or Files and these are used by the CPU (Central Processing Unit - the heart of the microcontroller) to control the operation of the chip. These files have names such as STATUS register, File Select Register, Timer1 HIGH, Timer1 LOW and the in/out port called GPIO or PORTA, PORTB. These files (or Registers) along with others, are in BANK0 - the core area of the chip, while other Registers such as OPTION register, Oscillator Calibration register, EEDATA register, TRIS (the files that determines if a pin will be input or output) and others are in BANK1.
To place data into these registers or read data from them, you must “switch banks.” This is called BANK SWITCHING and is done by adding an instruction to your program thus:
To change from the core area (Bank0) to Bank1, the instructions is:
bsf status, rp0 ;to get to Bank 1
To change from Bank1, back to the core area (your programming area), the instruction is:
bcf status, rp0 ;to get to bank 0
The STATUS file is located in both areas and that is why it can be used to switch from one bank to the other.
You must switch to Bank0 after accessing files in Bank1, to execute further instructions in your program
The fourth area is EEPROM area. This area contains 128 bytes of data that can be altered at any time during the running of a program and data will be retailed when power is removed. EPROM memory is not CODE area (your program area) or General Purpose Register memory. They are all separate. EPROM memory is very slow in writing but fast in reading. It can be written to a million times and needs no power to hold its memory.
Code space memory (flash memory) has about 100,000 write-cycle capability and cannot retain data without power.
General Purpose Register memory is STATIC RAM. These are the files from 20h to 5Fh (and more) that you use to store temporary data during the running of your program. It does not retain data without power.
The “w Register” is the “working Register” and transfers data from one file (or routine) to another.


All our projects come with a discussion and an explanation of “How the Circuit Works.”
Almost all the projects can be constructed using the circuit diagram and photos, but if it doesn’t work, you need to read the documentation.
Electronics engineers don’t like reading. That’s why we have made it easy to build our projects. All the PC boards have an overlay and nothing else is needed to put the project together.
But if you want to know how the circuit works or how the project was designed, you need to READ THE ARTICLE.

Going Further
No-one has produced projects as complex as our Dial Alarm-2 or Tic Tac Toe, using simple hand-assembly techniques and we have shown the capability of tiny micros.
But If you want to design something more complex, you will have to go to the next step by learning a “Programming Language.” This may be “BASIC,” or “C” or “JAL” or one of a number of other languages. These are all fully covered on the web - via a Google search. And, of course, these will open up a whole new field of expansion.
At least we can say: “we got you started.”

  • P2 (100 Helpful Hints)
  • P3 The XOR Trick

Colin Mitchell

Colin Mitchell



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