HT46R4A View Datasheet(PDF) - Holtek Semiconductor

Part Name

Description

Manufacturer

HT46R4A

Cost-Effective A/D Type 8-Bit MCU

Holtek Semiconductor 

HT46R4A

Data Memory

The Data Memory is a volatile area of 8-bit wide RAM

internal memory and is the location where temporary in-

formation is stored. Divided into two sections, the first of

these is an area of RAM where special function registers

are located. These registers have fixed locations and

are necessary for correct operation of the device. Many

of these registers can be read from and written to di-

rectly under program control, however, some remain

protected from user manipulation. The second area of

Data Memory is reserved for general purpose use. All

locations within this area are read and write accessible

under program control.

Structure

The two sections of Data Memory, the Special Purpose

and General Purpose Data Memory are located at con-

secutive locations. All are implemented in RAM and are

8 bits wide but the length of each memory section is dic-

tated by the type of microcontroller chosen. The start

address of the Data Memory for all devices is the ad-

dress ²00H². Registers which are common to all

microcontrollers, such as ACC, PCL, etc., have the

same Data Memory address.

00H

S p e c ia l P u r p o s e

D a ta M e m o ry

3FH

40H

G e n e ra l P u rp o s e

D a ta M e m o ry

FFH

H T46R 4A

Data Memory Structure

Note:

Most of the Data Memory bits can be directly

manipulated using the ²SET [m].i² and ²CLR

[m].i² with the exception of a few dedicated bits.

The Data Memory can also be accessed

through the memory pointer register MP.

General Purpose Data Memory

All microcontroller programs require an area of

read/write memory where temporary data can be stored

and retrieved for use later. It is this area of RAM memory

that is known as General Purpose Data Memory. This

area of Data Memory is fully accessible by the user pro-

gram for both read and write operations. By using the

²SET [m].i² and ²CLR [m].i² instructions individual bits

can be set or reset under program control giving the

user a large range of flexibility for bit manipulation in the

Data Memory.

Special Purpose Data Memory

This area of Data Memory is where registers, necessary

for the correct operation of the microcontroller, are

stored. Most of the registers are both readable and

writable but some are protected and are readable only,

the details of which are located under the relevant Spe-

cial Function Register section. Note that for locations

that are unused, any read instruction to these addresses

will return the value ²00H².

00H

IA R

01H

MP

02H

03H

04H

05H

ACC

06H

PCL

07H

TB LP

08H

TB LH

09H

0A H S TA TU S

0 B H IN T C 0

0C H

0D H

TM R 0

0E H TM R 0C

0FH

10H

TM R 1

11H TM R 1C

12H

PA

13H

PAC

14H

PB

15H

PBC

16H

PC

17H

PCC

18H

PD

19H

PDC

1A H P W M 0

1B H P W M 1

1C H

1D H

1 E H IN T C 1

1FH

20H

ADRL

21H

ADRH

22H

ADCR

23H

ACSR

: U n u s e d , re a d a s "0 0 "

Special Purpose Data Memory

Rev. 1.00

10

November 28, 2007

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