PIC Microcontroller Structure & Assembly Language

2.  electronic circuits that can be programmed to
carry out a vast range of tasks.
 family of specialized microcontroller chips
produced by MicrochipTechnology in
Chandler,Arizona.
 a processor with built in memory and RAM
and you can use it to control your projects.

4.  Memory unit
 Central Processing Unit
 Bus
 Input-output unit
 Serial communication
 Timer unit
 Watchdog
 Analog to Digital Converter (ADC)
 Program

5.  Microcontroller differs from a microprocessor in
many ways. First and the most important is its
functionality. In order for a microprocessor to be
used, other components such as memory, or
components for receiving and sending data
must be added to it. In short that means that
microprocessor is the very heart of the
computer. On the other hand, microcontroller is
designed to be all of that in one. No other
external components are needed for its
application because all necessary peripherals are
already built into it.

6.  Morse code keyers
 Robots
 Data logging instruments
 Phone dialers
 Clocks and timers
 Much, much more

7.  The PIC
 PIC16F84A
 A breadboard
 A set of resistors, capacitors and LEDs
 A power supply
 5V DC source
 A PIC Programmer
 MPLAB or another platform

10.  Contains the arithmetic logic unit
 Bit # 0 – 2
 Reset status of the PIC
 Bit # 3 and 4
 Bank selection bits
 Bit # 5 and 6
 Direct and indirect addressing – bit # 7

11.  Low level programming language for a
computer or other programmable device
specific to a particular computer architecture

13.  The PIC family has a very short range of
instructions with just only 35 instructions.
 All instructions have just about the same
format. First comes the name of the
instructions.Then, comes the instructions
fields.The fields may be none, one or two,
according to the instruction.
 The instruction could be filled with file
register (f), a bit address (b), constant data(k),
or destination selection (d).

14.  General purpose registers in which you can
put any value that you wish.

15.  The most basic operations that needs to be done will
be the value loading.These operations have to do
with loading a binary, decimal or hexadecimal value
on theW register or to a register.
 Declaring number base in loading a value:
 Binary
▪ b’01010010’
 Decimal
▪ D’35’
 Hexadecimal
▪ 0x1F
▪ 4fh

16.  movlw k
 Loads literal value k to the W register
 movwf f
 Moves the value from W register to file register f
 movf f,d
 Loads a value from the file register f. If destination
d is equal to 0 the result is stored in the W
register, if d is equal to 1 the result will stored back
to the file register f.

17.  bsf f , b
 Bit b in the file register f is Set(1).
 bcf f , b
 Bit b in the file register f is Cleared(0).
 btfss f , b
 If the bit 'b' in file register 'f' is 1, then the following instructions is not
executed. If the bit is 0, the instructions is executed normally.
 btfsc f , b
 If the bit 'b' in file register 'f' is 0, then the following instructions is not
executed. If the bit is 1, the instructions is executed normally.
 swapf f , d
 The upper and lower nibbles of file register 'f' are exchanged. If d is 0
the result is stored in theW register, if d is 1 the result is stored back to
the file register 'f'.

18.  GOTO k
 Send program flow directly to a program line or label.
 CALL k
 Send program flow directly to a program line or label. A RETURN instruction
will send the program flow back to the position where the CALL was made.
 RETURN
 This instruction will send the program flow to the last position, usually, this is
done by a previous CALL instruction
 RETLW k
 This instruction will send the program flow to the last position, usually, this is
done by a previous CALL instruction.Also, the W register will get the value k
on return.
 RETFIE
 This is a RETurn From Interrupt instruction.This instruction will send the
program flow back to the position where the last interrupt occurred and
caused the program flow to go to the interrupt vector (0x04h).

19.  RLF f , d
 Rotate Left through carry.The bits are rotated one position left
through the Carry. If d is 0 the result is stored in the W register, if d is 1
the result is stored back to the file register 'f'.
 RRF f , d
 Rotate Right through carry.The bits are rotated one position right
through the Carry. If d is 0 the result is stored in the W register, if d is 1
the result is stored back to the file register 'f'.
 INCF f , d
 The contents of register 'f' are increased by 1. If d is 0 the result is
stored in theW register, if d is 1 the result is stored back to the file
register 'f'.
 DECF f , d
 The contents of register 'f' are decreased by 1. If d is 0 the result is
stored in theW register, if d is 1 the result is stored back to the file
register 'f'.

20.  INCFSZ f , d
 The contents of register 'f' are increased by 1. If d is 0 the result
is stored in the W register, if d is 1 the result is stored back to the
file register 'f'. If the result is '0', the very next instruction is not
executed.
 DECFSZ f , d
 The contents of register 'f' are decreased by 1. If d is 0 the result
is stored in the W register, if d is 1 the result is stored back to the
file register 'f'. If the result is '0', the very next instruction and is
not executed.
 CLRF f
 The register 'f' is cleared.
 CLRW
 The working register W is cleared.

21.  ADDLW k
 Add the content of W register with a literal value and store the result in theW
register
 ADDWF f , d
 Add the content of W register with the content of a file register 'f'. If d is 0 the
result is stored in the W register, if d is 1 the result is stored back to the file
register 'f'.
 SUBLW k
 Subtract the content ofW register from a literal value and store the result in
theW register.
 SUBWF f , d
 Subtract the content ofW register from the content of a file register 'f'. If d is 0
the result is stored in theW register, if d is 1 the result is stored back to the file
register 'f'.
 COMF f , d
 The contents of the file register 'f' are complemented. If d is 0 the result is
stored in theW register, if d is 1 the result is stored back to the file register 'f'.

22.  ANDLW k
 Logic AND between the contents ofW and the literal value k.
The results is stored back to W.
 ANDWF f , d
 Logic AND between the content ofW register with the content
of a file register 'f'. If d is 0 the result is stored in theW register, if
d is 1 the result is stored back to the file register 'f'.
 IORLW k
 Logic OR between the contents ofW and the literal value k.The
results is stored back toW.
 IORWF f , d
 Logic OR between the content ofW register from the content of
a file register 'f'. If d is 0 the result is stored in the W register, if d
is 1 the result is stored back to the file register 'f'.

23.  XORLW k
 Logic EXCLUSIVE OR between the contents ofW
and the literal value k.The results is stored back to
W.
 XORWF f , d
 Logic EXCLUSIVE OR between the content ofW
register from the content of a file register 'f'. If d is
0 the result is stored in theW register, if d is 1 the
result is stored back to the file register 'f'.

24.  NOP
 This instructions is the No Operations instructions
and does nothing at all.
 CLRWDT
 This instructions will reset theWatchdogTimer
 SLEEP
 This instructions will put the chip into Sleep mode

25.  All these instructions set the Z flag of the
status register if their result is zero.
Otherwise, the Z flag is cleared.

26. Result Carry Zero
Positiv
e
1 0
Zero 1 1
Negati
ve
0 0

27.  MPLAB IDE – coding and compiling
 Proteus – circuit simulation
 Pic Programmer – use to interface the
program in PIC chip.