HT56RB688_13 datasheet(28/164 Pages) HOLTEK

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Data Memory

Bank Number

3~31

Special Purpose

Data Memory

Start Address

Common: 00H

End Address

Common: 7FH

General Purpose and

LCD Data Memory

Start Address

80H

End Address

FFH

CFH

FFH

Data Memory Content

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 sections, the Special Purpose Data

Memory and the General Purpose Data Memory.

The start address of the Data Memory for the device is the address ²00H². Registers which are

common to the microcontroller, such as ACC, PCL, etc., have the same Data Memory address. The

LCD Memory is mapped into Bank 1 and Bank 2. Banks 3 to 31 contain only General Purpose Data

Memory for the device 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.

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 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. For the device with larger Data Memory capacities, the General Purpose Data Memory, in

addition to being located in Bank 0, is also stored in Banks 3 to Bank 31.

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 read and write type but some are protected

and are read only, the details of which are located under the relevant Special Function Register section.

Note that for locations that are unused, any read instruction to these addresses will return the unknow

value. The Special Function registers are mapped into all banks and can therefore be accessed from

any bank location.

Display Memory

The data to be displayed on the LCD or LED display is stored in an area of fully accessible Data Memory.

By writing to this area of RAM, the display output can be directly controlled by the application program.

As this Memory exists in Bank 1 and Bank 2, but have addresses which map into the General Purpose

Data Memory, it is necessary to first ensure that the Bank Pointer is set to the value 01H or 02H before

accessing the Display Memory. The Display Memory can only be accessed indirectly using the Memory

Pointer MP1 and the indirect addressing register IAR1. When the Bank Pointer is set to 01H or 02H to

select Data Memory Bank 1 or Bank 2 to access the Display Memory, if any addresses with a value less

than 80H are read, the Special Purpose Data Memory in Bank 0 will be accessed. Also, if the Bank

Pointer is set to 01H or 02H to select Data Memory Bank 1 or Bank 2, if any addresses higher than the

last address in Bank 1 or Bank 2 are read, then a value of 00H will be returned.

Rev. 1.10

April 15, 2013

HT56RB688

TinyPowerTM A/D type Smart Card OTP MCU

with LCD, DAC, ISO 7816 and USB Interfaces

HT56RB688 Datasheet(PDF) 28 Page - Holtek Semiconductor Inc

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