HT46R0664 datasheet(19/92 Pages) HOLTEK

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HT46R0664

Enhanced A/D+LCD 8-Bit OTP MCU

Data Memory

The Data Memory is an 8-bit wide RAM internal memory and is the location where temporary

information is stored.

Divided into three 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 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 three banks, all of which are implemented in 8-bit wide

RAM. The Data Memory located in Bank 0 is subdivided into two sections, the Special Purpose

Data Memory and the General Purpose Data Memory. The start address of the Data Memory is the

address “00H”. The LCD Memory is mapped into Bank 1. Bank 2 contains only General Purpose

Data Memory. As the Special Purpose Data Memory registers are mapped into all bank areas, they

can subsequently be accessed from any bank location.

00H

FFH

3FH

40H

Special Purpose

Data Memory

General Purpose

Data Memory

Bank 1

LDC Memory

Bank 0

Bank 2

Data Memory Structure

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 program for both read and

write operations. By using the “SET [m].i” and “CLR [m].i” 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. For this device, the General Purpose Data Memory, in addition to being located in

Bank 0, is also stored in Bank 2.

Bank0

Bank1 (LCD RAM)

Bank2

40H~FFH

40H~56H

40H~5FH

HT46R0664 Datasheet(PDF) 19 Page - Holtek Semiconductor Inc

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