HT46R321 데이터 시트보기 (PDF) - Holtek Semiconductor
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HT46R321 Datasheet PDF : 45 Pages
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HT46R321
pointer is decremented, using a RET or RETI instruc-
tion, the interrupt will be serviced. This feature prevents
a stack overflow allowing the programmer to use the
structure more easily. In a similar case, if the stack is full
and a ²CALL² is subsequently executed, stack overflow
occurs and the first entry will be lost. Only the most re-
cent 6 return addresses are stored.
Data Memory - RAM
The data memory is divided into two functional groups:
special function registers and general purpose data
memory. The general purpose memory has a structure
of 88´8 bits. Most locations are read/write, but some
are read only.
The remaining space between the end of the Special
Purpose Data Memory and the beginning of the General
Purpose Data Memory is reserved for future expanded
usage, reading these locations will obtain a result of
²00H². The general purpose data memory, addressed
from 28H to 7FH, is used for user data and control infor-
mation under instruction commands. All of the data
memory areas can handle arithmetic, logic, increment,
decrement and rotate operations directly. Except for
some dedicated bits, each bit in the data memory can
be set and reset by the ²SET [m].i² and ²CLR [m].i² in-
structions. They are also indirectly accessible through
memory pointer register, MP.
Indirect Addressing Register
Location 00H is an indirect addressing register that is
not physically implemented. Any read/write operation on
[00H] accesses data memory pointed to by the MP
register. Reading location 00H itself indirectly will return
the result 00H. Writing indirectly results in no operation.
The memory pointer register, MP, is a 7-bit register. The bit 7
of MP is undefined and read as ²1².
Accumulator
The accumulator is closely related to ALU operations
and can carry out immediate data operations. Any data
movement between two data memory locations must
pass through the accumulator.
Arithmetic and Logic Unit - ALU
This circuit performs 8-bit arithmetic and logic opera-
tions. The ALU provides the following functions:
· Arithmetic operations - ADD, ADC, SUB, SBC, DAA
· Logic operations - AND, OR, XOR, CPL
· Rotation - RL, RR, RLC, RRC
· Increment and Decrement - INC, DEC
· Branch decision - SZ, SNZ, SIZ, SDZ ....
The ALU not only saves the results of a data operation but
also changes the status register.
00H
In d ir e c t A d d r e s s in g R e g is te r
01H
MP
02H
03H
04H
05H
ACC
06H
PCL
07H
TB LP
08H
TB LH
09H
0A H
STATU S
0B H
IN T C
0C H
0D H
TM R
0E H
TM R C
0FH
10H
11H
12H
PA
13H
PAC
14H
PB
15H
PBC
16H
17H
18H
PD
19H
PDC
1A H
1B H
1C H
PW M 0
1D H
PW M 1
1E H
1FH
O PAC
20H
ADRL
21H
ADRH
22H
ADCR
23H
ACSR
24H
S p e c ia l P u r p o s e
D a ta M e m o ry
:U nused
27H
28H
G e n e ra l P u rp o s e
D a ta M e m o ry
(8 8 B y te s )
7FH
R e a d a s "0 0 "
RAM Mapping
Rev. 1.00
9
August 3, 2007
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