HT68F13 datasheet(24/161 Pages) HOLTEK

24 / 161 page

SpecialFunctionRegisterDescription

Most of the Special Function Register details will be described in the relevant functional section.

However, several registers require a separate description in this section.

IndirectAddressingRegisters

- IAR0,IAR1

The Indirect Addressing Registers, IAR0 and IAR1, although having their locations in normal RAM

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 Pointers, MP0 or MP1. 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.

IndirectAddressingProgramExample

data .section

¢data¢

adres1 db ?

adres2 db ?

adres3 db ?

adres4 db ?

block db ?

code .section at 0

¢code¢

org

00h

start:

mov

a,04h

; setup size of block

mov

block,a

mov

a,offset adres1

; Accumulator loaded with first RAM address

mov

mp0,a

; setup memory pointer with first RAM address

loop:

clr

IAR0

; clear the data at address defined by MP0

inc

mp0

; increment memory pointer

sdz

block

; check if last memory location has been cleared

p loop

continue:

The important point to note here is that in the example shown above, no reference is made to specific

RAMaddresses.

MemoryPointers

- 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 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. Note that for the HT68F13 device, bit 7 of the

Memory Pointers is not required to address the full memory space. When bit 7 of the Memory Pointers

for HT68F13 device is read, a value of 1 will be returned. The following example shows how to clear a

section of four Data Memory locations already defined as locations adres1 to adres4.

Rev.1.10

February9,2011

HT68F13/HT68F14/HT68F15

EnhancedI/OFlashType MCU

HT68F13 датащи(PDF) 24 Page - Holtek Semiconductor Inc

HT68F13 датащи(HTML) 24 Page - Holtek Semiconductor Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

датащи скачать

ссылки URL