HT46R016 데이터 시트보기 (PDF) - Holtek Semiconductor
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HT46R016 Datasheet PDF : 91 Pages
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HT46R016/HT46R017
Enhanced A/D Type 8-Bit OTP MCU
Special Function Register
To ensure successful operation of the microcontroller, certain internal registers are implemented in
the Data Memory area. These registers ensure correct operation of internal functions such as timers,
interrupts, etc., as well as external functions such as I/O data control. The location of these registers
within the Data Memory begins at the address "00H". Any unused Data Memory locations between
these special function registers and the point where the General Purpose Memory begins is reserved
and attempting to read data from these locations will return a value of "00H".
Indirect Addressing Registers – IAR0, IAR1
The Indirect Addressing Registers, IAR0 and IAR1, although having their locations in normal RAM
register space, do not actually physically exist as normal registers. The method of indirect addressing
for RAM data manipulation uses these Indirect Addressing Registers and Memory Pointers, in
contrast to direct memory addressing, where the actual memory address is specified. Actions on the
IAR0 and IAR1 registers will result in no actual read or write operation to these registers but rather
to the memory location specified by their corresponding Memory Pointer, MP0 or MP1. Acting as
a pair, IAR0 with MP0 and IAR1 with MP1 can together access data from the Data Memory. As
the Indirect Addressing Registers are not physically implemented, reading the Indirect Addressing
Registers indirectly will return a result of "00H" and writing to the registers indirectly will result in
no operation.
Memory Pointers – MP0, MP1
Two Memory Pointers, known as MP0 and MP1 are provided. These Memory Pointers are
physically implemented in the Data Memory and can be manipulated in the same way as normal
registers providing a convenient way with which to indirectly address and track data. When any
operation to the relevant Indirect Addressing Registers is carried out, the actual address that the
microcontroller is directed to, is the address specified by the related Memory Pointer. The following
example shows how to clear a section of four Data Memory locations already defined as locations
adres1 to adres4.
Indirect Addressing Program Example
data . section ‘data’
adres1
db
?
adres2
db
?
adres3
db
?
adres4
db
?
block
db
?
code. section at 0 code
org 00h
start:
mov a,04h
mov block,a
mov a,offset adres1
mov mp0,a
loop:
clr IAR0
inc mp0
sdz block
jmp loop
continue:
; setup size of block
; Accumulator loaded with first RAM address
; setup memory pointer with first RAM address
; clear the data at address defined by MP0
; increment memory pointer
; check if last memory location has been cleared
The important point to note here is that in the example shown above, no reference is made to specific
Data Memory addresses.
Rev. 1.00
20
July 16, 2012
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