HT95R34 datasheet(14/59 Pages) HOLTEK

14 / 59 page

HT95R34

Rev. 1.10

February 18, 2009

Addressing Registers are not physically implemented,

reading the Indirect Addressing Registers indirectly will

return a result of

²00H² and writing to the registers indi-

rectly will result in no operation.

Memory Pointer

- MP0, MP1

For all devices, 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 pro-

viding a convenient way with which to address and track

data. When any operation to the relevant Indirect Ad-

dressing Registers is carried out, the actual address that

the microcontroller is directed to, is the address speci-

fied by the related Memory Pointer. MP0, together with

Indirect Addressing Register, IAR0, are used to access

data from Bank 0 only, while MP1 and IAR1 are used to

access data from Banks 1~10.

The following example shows how to clear a section of four RAM locations already defined as locations adres1 to

adres4.

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

jmp loop

continue:

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

Bank Pointer

- BP

The Data Memory RAM is divided into eleven banks, known as Bank 0~Bank 10. All of the Special Purpose Registers

are contained in Bank 0. Selecting the required Data Memory area is achieved using the Bank Pointer. If data in Bank 0

is to be accessed, then the BP register must be loaded with the value

²00², while if data in Bank 1 is to be accessed,

then the BP register must be loaded with the value

²01² and so on for the other registers. Using Memory Pointer MP0

and Indirect Addressing Register IAR0 will always access data from Bank 0, irrespective of the value of the Bank

Pointer.

The Data Memory is initialised to Bank 0 after a reset, except for a WDT time-out reset in the Power Down Mode, in

which case, the Data Memory bank remains unaffected. It should be noted that Special Function Data Memory is not af-

fected by the bank selection, which means that the Special Function Registers can be accessed from Bank 0 to Bank

10. Directly addressing the Data Memory will always result in Bank 0 being accessed irrespective of the value of the

Bank Pointer.

B P 3 , B P 2 , B P 1 , B P 0

D a t a M e m o r y

1 0

1 1 ~ 1 5

B a n k P o i n t e r

b 7

b 0

B P 0

B a n k 0

B a n k 1

B a n k 2

B a n k 3

B a n k 4

B a n k 5

B a n k 6

B a n k 7

B a n k 8

B a n k 9

B a n k 1 0

N o t i m p l e m e n t e d , r e a d a s " 0 "

N o t u s e d , m u s t b e r e s e t t o " 0 "

B P 1

B P 2

B P 3

HT95R34 датащи(PDF) 14 Page - Holtek Semiconductor Inc

HT95R34 датащи(HTML) 14 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

датащи скачать

ссылки URL