HT82B40A datasheet(11/54 Pages) HOLTEK

11 / 54 page

HT82B40R/HT82B40A

Rev. 1.70

November 5, 2014

Special Purpose Data Memory

This area of Data Memory is where registers, necessary

for the correct operation of the microcontroller, are

stored. It is divided into two banks, Bank 0 and Bank1.

Most of the registers are both readable and writeable

but some are protected and are readable only, the de-

tails of which are located under the relevant Special

Function Register section. Note that for locations that

are unused, any read instruction to these addresses will

return the value

²00H².

The Special Purpose Registers for the USB interface

are stored in Bank 1 which can only be accessed by first

setting the Bank Pointer to a value of 01H and then us-

ing Indirect Addressing Register IAR1 and Memory

Pointer MP1. Bank 1 can only be accessed indirectly us-

ing the MP1 Memory Pointer, direct addressing is not

possible.

Special Function Registers

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 be-

gins at the address 00H. Any unused Data Memory lo-

cations between these special function registers and the

point where the General Purpose Memory begins is re-

served and attempting to read data from these locations

will return a value of 00H.

Indirect Addressing Register

- IAR0, IAR1

The Indirect Addressing Registers, IAR0 and IAR1, al-

though having their locations in normal RAM register

space, do not actually physically exist as normal regis-

ters. The method of indirect addressing for RAM data

manipulation uses these Indirect Addressing Registers

and Memory Pointers, in contrast to direct memory ad-

dressing, where the actual memory address is speci-

fied. 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 corre-

sponding Memory Pointer, MP0 or MP1. Acting as a

pair, IAR0 and MP0 can together only access data from

Bank 0, while the IAR1 and MP1 register pair can ac-

cess data from both Bank 0 and Bank 1. As the Indirect

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 can only ac-

cess data in Bank 0 while MP1 can access both banks.

0 0 H

0 1 H

0 2 H

0 3 H

0 4 H

0 5 H

0 6 H

0 7 H

0 8 H

0 9 H

0 A H

0 B H

0 C H

0 D H

0 E H

0 F H

1 0 H

1 1 H

1 2 H

1 3 H

1 4 H

1 5 H

1 6 H

1 7 H

1 8 H

1 9 H

1 A H

1 B H

1 C H

1 D H

1 E H

1 F H

2 0 H

2 1 H

2 2 H

2 3 H

: U n u s e d r e a d a s " 0 "

I A R 0

M P 0

I A R 1

M P 1

B P

A C C

P C L

T B L P

T B L H

W D T S

S T A T U S

I N T C

T M R 0

T M R 0 C

T M R 1 H

T M R 1 L

T M R 1 C

P A

P A C

P B

P B C

P C

P C C

P D

P D C

P E

P E C

T B H P

U S C

U S R

S C C

4 0 H

4 1 H

4 2 H

4 3 H

4 4 H

4 5 H

4 6 H

4 7 H

4 8 H

4 9 H

4 A H

U S B _ S T A T

P I P E _ C T R L

A W R

S T A L L

P I P E

S I E S

M I S C

E N D P T _ E N

F I F O 0

F I F O 1

F I F O 2

B a n k 0

B a n k 1

Special Purpose Data Memory

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