HT95R34 datasheet(13/59 Pages) HOLTEK

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HT95R34

Rev. 1.10

February 18, 2009

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. As the General Purpose Data Memory is

located within 11 different banks, it is first necessary to

ensure that the Bank Pointer is properly set to the cor-

rect value before accessing the General Purpose Data

Memory. Only Bank 0 data can be read directly. Indirect

Addressing of Bank 0 is executed using Indirect Ad-

dressing Register IAR0 and Memory Pointer MP0. Data

in Banks 1~10 can only be read indirectly using Indirect

Addressing Register IAR1 and Memory Pointer MP1.

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

writeable 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. Although the Special Pur-

pose Data Memory registers are located in Bank 0, they

will still be accessible even if the Bank Pointer has se-

lected Banks 1~10.

Special Function Registers

To ensure successful operation of the microcontroller,

certain internal registers are implemented in the RAM

Data Memory area. These registers ensure correct op-

eration of internal functions such as timers, interrupts,

watchdog, etc., as well as external functions such as I/O

data control. The location of these registers within the

RAM Data Memory begins at the address

²00H². Any

unused Data Memory locations between these special

function registers and the point where the General Pur-

pose Memory begins is reserved for future expansion

purposes, attempting to read data from these locations

will return a value of

²00H².

Indirect Addressing Register

- IAR0, IAR1

The Indirect Addressing Registers, IAR0 and IAR1, al-

though having their locations in normal RAM register

space, do not actually physically exist as normal regis-

ters. The method of indirect addressing for RAM data

manipulation uses these Indirect Addressing Registers

and Memory Pointers, in contrast to direct memory ad-

dressing, where the actual memory address is speci-

fied. Actions on the IAR0 and IAR1 registers will result in

no actual read or write operation to these registers but

rather to the memory location specified by their corre-

sponding Memory Pointer, MP0 or MP1. Acting as a

pair, IAR0 and MP0 can together only access data from

Bank 0, while the IAR1 and MP1 register pair can ac-

cess data from both Bank 0 and Bank 1. As the Indirect

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 b y t e , r e a d a s " 0 0 "

3 F H

3 0 H

2 0 H

2 1 H

2 2 H

2 3 H

2 4 H

2 5 H

2 6 H

2 7 H

I A R 0

M P 0

I A R 1

M P 1

B P

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 H

T M R 0 L

T M R 0 C

T M R 1 H

T M R 1 L

T M R 1 C

P A

P A C

P C

P C C

P D

P D C

P E

P E C

I N T C 1

D T M F C

D T M F D

D T R X C

D T R X D

R T C C

M O D E

2 B H

M F I C

P F D C

P F D D

2 C H

2 D H

2 E H

2 F H

Special Purpose Data Memory Structure

HT95R34 数据表(PDF) 13 Page - Holtek Semiconductor Inc

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