HT56R67 datasheet(19/104 Pages) HOLTEK

19 / 104 page

HT56R67/HT56R668/HT56C668/HT56R678/HT56C678/HT56R688

Rev. 1.20

March 4, 2010

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 three sections, the first

of these is an area of RAM where special function regis-

ters 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

directly 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. The third area is reserved for the

LCD Memory. This special area of Data Memory is

mapped directly to the LCD display so data written into

this memory area will directly affect the displayed data.

The addresses of the LCD Memory area overlap those

in the General Purpose Data Memory area. Switching

between the different Data Memory banks is achieved

by setting the Bank Pointer to the correct value.

Structure

The Data Memory is subdivided into several banks, all

of which are implemented in 8-bit wide RAM. The Data

Memory located in Bank 0 is subdivided into two sec-

tions, the Special Purpose Data Memory and the Gen-

eral Purpose Data Memory.

The start address of the Data Memory for all devices is

the address

²00H². Registers which are common to all

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

same Data Memory address. The LCD Memory is

mapped into Bank 1. Banks 2 to 12 contain only General

Purpose Data Memory for those devices with larger

Data Memory capacities. As the Special Purpose Data

Memory registers are mapped into all bank areas, they

can subsequently be accessed from any bank location.

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

D a t a M e m o r y

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

4 0 H

F F H

3 F H

B a n k 0

B a n k 2

B a n k 1

L C D

M e m o r y

B a n k 3

B a n k 1 2

Data Memory Structure

Bank Number

0123456789

HT56R67

- 2304 Bytes

SPDM

Common 00H

Common 3FH

GPDM

40H

FFH

70H

FFH FFH FFH FFH FFH FFH FFH FFH FFH FFH FFH

HT56R668

HT56C668

HT56R678

HT56C678

HT56R688

- 2304 Bytes

SPDM

Common 00H

Common 3FH

GPDM

40H

FFH BFH FFH FFH FFH FFH FFH FFH FFH FFH FFH FFH FFH

Data Memory Content

Note:

SPDM: Special Purpose Data Memory

GPDM: General Purpose Data Memory

SA: Start Address

EA: End Address

x: Not implemented

HT56R67 Datasheet(PDF) 19 Page - Holtek Semiconductor Inc

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