MICRO-CONTROLLER MOTOROLA HCS12Instruction Set

Mechatronics

Department

Faculty of EngineeringAin Shams Univeristy

Memory on Chip

A B

X

Y

SP

PC

N Z V C

Processor Memory Specia

l Regist

er

RAM

ROM

MemoryPort T

Port

T

DDRT

DD

RT

MC68HC12 “Stepper Motor Control”

Port T3|2|1|0 $242

MC68HC12 “Stepper Motor Control”

Size equ 4;

PTT equ $240; Address of port T

DDRT equ $242; Data direction register for port T

org $4000;

------------------------------------------------------------------

main movb #$FF, DDRT; Set port T for output

Run ldaa #size; initialize counter in A

ldx #steps; Point to the steps in memory

step movb 1, x+, PTT; step the motor

dbne A, step; Decrement A and check if it’s zero

bra run;

Step Counter

Port T is a part of memory having Address $ 240

Data direction register of Port T is a part of memory having Address $ 242

steps 1001

steps +1

1010

steps +2

1001

steps +3

0110

Move Data instructionMove Data instructionMove Data instructionMove Data instructionDecision Making

Flow Control

MC68HC12 “Stepper Motor Control”

steps 0101

steps +1

1001

steps +2

1010

steps +3

0110

A B

X

Y

SP

PC

N Z V C

!4ldaa#4ldx#steps

Steps

Port Tmovb 1, x+, PTT

Steps +1

0101

dbne A, step!3

$4003$4005$4008$400B$400F$4008

movb 1, x+, PTT

$400B

Steps +2

1001$400F

dbne A, step!2

$4008

movb 1, x+, PTT

$400B

Steps +3

1010

$400F

dbne A, step!1

$4008

movb 1, x+, PTT

Steps +4

0110

$400B

dbne A, step

$400F

!0brarun

$4003

ldx#stepsldaa#4!4

Steps

$4005$400B

HCS12 Instruction Set

Move data. Modify data. Decision making. Flow control.

Push and Pull instructions

$5005

….

$5006

….

$5007

….

$5008

….

$5009

….

$500A

….

$500B

….

$500C

….

A B

X

Y

SP

PC

N Z V C

$5005

PULA;

Stack Pointer

Sta

ck

$FF

Sta

ck

PSHA;

$5006

Bit manipulation instructions

$5005

….

$5006

….

$5007

….

$5008

….

$5009

….

$500A

….

$500B

….

$500C

….

BSET$5005,$6A;

$B0$B0

$6A

% 1 0 1 1 0 0 0 0% 0 1 1 0 1 0 1 0

% 1 1 1 1 1 0 1 0

$FA

Eng. Mohamed Mahmoud Hamdy

Eng. Mostafa Ahmed Arafa

Prepared by: