HT46R01A datasheet(11/58 Pages) HOLTEK

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HT46R01A

Rev. 1.10

August 13, 2008

Memory Pointers

- MP0, MP1

Two Memory Pointers, known as MP0 and MP1 are pro-

vided. These Memory Pointers are physically imple-

mented in the Data Memory and can be manipulated in

the same way as normal registers providing a conve-

nient way with which to address and track data. When

any operation to the relevant Indirect Addressing Regis-

ters is carried out, the actual address that the

microcontroller is directed to, is the address specified by

the related Memory Pointer, bit 7 of the Memory

Pointers is not required to address the full memory

space. It must be noted that when bit 7 of the Memory

Pointers for these devices is read, a value of

²1² will be

returned. The following example shows how to clear a

section of four Data Memory locations already defined as

locations adres1 to adres4.

data .section

¢data¢

adres1

db ?

adres2

db ?

adres3

db ?

adres4

db ?

block

db ?

code .section at 0

¢code¢

org

00h

start:

mov a,04h

; setup size of block

mov block,a

mov a,offset adres1; Accumulator loaded with first RAM address

mov mp0,a

; setup memory pointer with first RAM address

loop:

clr IAR0

; clear the data at address defined by MP0

inc mp0

; increment memory pointer

sdz block

; check if last memory location has been cleared

jmp loop

continue:

The important point to note here is that in the example shown above, no reference is made to specific Data Memory ad-

dresses.

S p e c i a l P u r p o s e

D a t a M e m o r y

0 0 H

0 1 H

0 2 H

0 3 H

0 4 H

0 5 H

0 6 H

0 7 H

0 8 H

0 9 H

0 A H

0 B H

0 C H

0 D H

0 E H

0 F H

1 0 H

1 1 H

1 2 H

1 3 H

1 4 H

1 5 H

1 6 H

1 7 H

1 8 H

1 9 H

1 A H

1 B H

1 C H

1 D H

1 E H

1 F H

: U n u s e d ,

r e a d a s " 0 0 "

G e n e r a l P u r p o s e

D a t a M e m o r y

( 6 4 B y t e s )

5 F H

2 0 H

I n d i r e c t A d d r e s s i n g R e g i s t e r 0

M P 0

I n d i r e c t A d d r e s s i n g R e g i s t e r 1

M P 1

A C C

P C L

T B L P

T B L H

W D T S

S T A T U S

I N T C 0

T M R 0

T M R 0 C

P A

P A C

P A P U

P A W K

C T R L 0

C T R L 1

A D R

A D C R

A C S R

P W M

Special Purpose Data Memory

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