16. •
•
PIC Programming
Chapter 2: Programming Microcontrollers
You certainly know that it is not enough just to connect the microcontroller to other components and turn
the power supply on to make it work, don't you? There is something else that must be done. The
microcontroller needs to be programmed to be capable of performing anything useful. If you think that it is
complicated, then you are mistaken. The whole procedure is very simple. Just read the following text and
you will change your mind.
2. 1 PROGRAMMING LANGUAGES
2.2 THE BASICS OF C PROGRAMMING LANGUAGE
2.3 COMPILER MIKROC PRO FOR PIC
2.1 PROGRAMMING LANGUAGES
P,og111mmlng
miCl"ocOntrolltr
....___
CPU f
,1000,0,,010,,
1100010001000
1000010,001010
100,0 00101000
,___
_
0001C1 1 1001 DO
11000101010010
0,0100 1 10010,0
11010101010010
110001 1 010•01<)
Bin.
101
1001101
1
100
10
0
,00,0011
100
001
100110 10
101
101
1
110101<1'00
IOHC01101
0
100
l��w.��� Hex.
10
1
100011
1111CIOIOC 1FCJ.3AA7
�IA
--- �I
Executlvo code In binary
and hexadecimal format
The microcontroller executes the
program loaded in its Flash memory.
This is the so called executable code
comprised of seemingly meaningless
sequence of zeros and ones. It is
organized in 12-, 14- or 16-bit wide
words, depending on the
microcontroller's architecture. Every
word is considered by the CPU as a
command being executed during the
operation of the microcontroller. For
practical reasons, as it is much easier
for us to deal with hexadecimal
number system, the executable code is
often represented as a sequence of
hexadecimal numbers called a Hex
code. It used to be written by the
programmer. All instructions that the
microcontroller can recognize are together called the Instruction set. As for PIC microcontrollers the
programming words of which are comprised of 14 bits, the instruction set has 35 different instructions in total.
CPU I
ProgrwnrTW'IQ
�lnlller
.....
1010
Progl'lm OJC«Mlon
0001
110
'01010011001 0
, 101ci1010.,ooto
11000,·,0101010
Bin
1O11GOl10t1100
100100•0011100
GOIIQ)ttOIOt0•
1011ff0
1010100
1011<0110I0100
:g:,1:=, Hex.
101KXJ011
Ill- 2FCDM7
F4lEOC2111
0Mffll641
Exe<ulve axle 1h buwy
and hlllCllddnel format
Program
compll1111an
....
Assembly language
lncnm8111
lhct ml, I
ma,,f ml,.,,
mo,r,ofPORT8
goto Loop
0ecre,_.,,
dod ant. I
mavf mt,w
mawtlPORlB
go1o Loop
As the process of
writing executable code
was endlessly tiring,
the first 'higher'
programming language
called assembly
language was created.
The truth is that it
made the process of
programming more
complicated, but on the
other hand the process
of writing program
stopped being a
nightmare. Instructions
in assembly language are represented in the form of meaningful abbreviations, and the process of their
compiling into executable code is left over to a special program on a PC called compiler. The main advantage
m
