HT45R22E Holtek Semiconductor, HT45R22E Datasheet - Page 13

• Manufacturer Part Number: HT45R22E
• Description: Remote Type 8-bit OTP MCU
• Manufacturer: Holtek Semiconductor

tempreg1 db
tempreg2 db
mov a,06h
mov tblp,a
tabrdl
dec tblp
tabrdl
org 0F00h
dc
RAM Data Memory
The Data Memory is a volatile area of 8-bit wide RAM in-
ternal memory and is the location where temporary in-
formation is stored.
Structure
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 cor-
rect operation of the device. Many of these registers can
be read from and written to directly under program con-
trol, however, some remain protected from user manipu-
lation. 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 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 ad-
dress of the Data Memory for all devices is the address
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
Rev. 1.00
00H .
Table Read Program Example
:
:
:
:
:
:
00Ah, 00Bh, 00Ch, 00Dh, 00Eh, 00Fh, 01Ah, 01Bh
:
:
tempreg1
tempreg2
?
?
; temporary register #1
; temporary register #2
; initialise table pointer - note that this address
; is referenced
; to the last page or present page
; transfers value in table referenced by table pointer
; to tempregl
; data at prog. memory address 0F06H transferred to
; tempreg1 and TBLH
; reduce value of table pointer by one
; transfers value in table referenced by table pointer
; to tempreg2
; data at prog.memory address 0F05H transferred to
; tempreg2 and TBLH
; in this example the data 1AH is transferred to
; tempreg1 and data 0FH to register tempreg2
; the value 00H will be transferred to the high byte
; register TBLH
; sets initial address of last page
13
area of Data Memory is fully accessible by the user pro-
gram for both read and write operations. By using the
can be set or reset under program control giving the
user a large range of flexibility for bit manipulation in the
Data Memory.
Note:
SET [m].i and CLR [m].i instructions individual bits
Most of the Data Memory bits can be directly
manipulated using the SET [m].i and CLR
[m].i with the exception of a few dedicated bits.
The Data Memory can also be accessed
through the memory pointer registers.
Data Memory Structure
HT45R22E
March 17, 2010
www.DataSheet4U.com