HT49CA1 View Datasheet(PDF) - Holtek Semiconductor
Part Name
Description
MFG CO.
'HT49CA1' PDF : 58 Pages View PDF
HT49RA1/HT49CA1
tempreg1 db ?
tempreg2 db ?
:
:
mov
a,06h
mov
tabrdl
tblp,a
:
:
tempreg1
dec
tblp
; 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 ²F06H² transferred to
; tempreg1 and TBLH
; reduce value of table pointer by one
tabrdl tempreg2
:
:
org
F00h
; transfers value in table referenced by table pointer
; to tempreg2
; data at prog.memory address ²F05H² transferred to
; tempreg2 and TBLH
; in this example the data ²1AH² is transferred to
; tempreg1 and data ²0FH² to register tempreg2
; the value ²00H² will be transferred to the high byte
; register TBLH
; sets initial address of last page (for HT49RA1)
Dc
00Ah, 00Bh, 00Ch, 00Dh, 00Eh, 00Fh, 01Ah, 01Bh
:
:
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. 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
S p e c ia l
P u rp o s e
00H
D a ta
M e m o ry
1FH
B ank 1
LC D
M e m o ry
B ank 0
G e n e ra l
P u rp o s e
D a ta
M e m o ry
5FH
40H
60H
60H
FFH
B ank 0
B ank 1
Data Memory Structure
Note:
Most of the Data Memory bits can be directly
manipulated using the ²SET [m].i² and ²CLR
[m].i² with the exception of a few dedicated bits.
The Data Memory can also be accessed
through the memory pointer registers
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 other Memory areas, switching between the two
areas is achieved by setting the Bank Pointer to the cor-
rect value.
Structure
The Special Purpose and General Purpose Data Mem-
ory are located at consecutive locations. All are imple-
mented in RAM and are 8 bits wide but the length of
each memory section is dictated by the type of
microcontroller chosen. The start address of the Data
Memory for all devices is the address 00H. Registers
which are common to all microcontrollers, such as ACC,
PCL, etc., have the same Data Memory address. The
LCD Data Memory is mapped into Bank 1 of the Data
Memory, however, only the lower four bits are used. The
higher four bits, if read by the program will return a zero
value. The start of LCD Data Memory for all devices is
the address 40H. However, since the LCD Data Memory
is located in Bank 1, to access this area the Bank
Pointer must first be set to a value of 01H. Note that after
power-on the contents of the Data Memory, including
Rev. 1.10
10
March 30, 2014
Share Link: 
