HT82K96E datasheet(9/44 Pages) HOLTEK

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HT82K96E

Rev. 2.00

October 11, 2007

Data Memory

- RAM for Bank 1

The special function registers used in USB interface are

located in RAM bank 1. In order to access Bank1 regis-

ter, only the Indirect addressing pointer MP1 can be

used and the Bank register BP should set to 1. The map-

ping of RAM bank 1 is as shown.

Indirect Addressing Register

Location 00H and 02H are indirect addressing registers

that are not physically implemented. Any read/write op-

eration of [00H] ([02H]) will access data memory pointed

to by MP0 (MP1). Reading location 00H (02H) itself indi-

rectly will return the result 00H. Writing indirectly results

in no operation.

The indirect addressing pointer (MP0) always point to

Bank0 RAM addresses no matter the value of Bank

The indirect addressing pointer (MP1) can access

Bank0 or Bank1 RAM data according the value of BP is

set to 0 or 1 respectively.

The memory pointer registers (MP0 and MP1) are 8-bit

registers.

Accumulator

The accumulator is closely related to ALU operations. It

is also mapped to location 05H of the data memory and

can carry out immediate data operations. The 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.

Status Register

- STATUS

This 8-bit register (0AH) contains the zero flag (Z), carry

flag (C), auxiliary carry flag (AC), overflow flag (OV),

power down flag (PDF), and watchdog time-out flag

(TO). It also records the status information and controls

the operation sequence.

With the exception of the TO and PDF flags, bits in

the status register can be altered by instructions like

most other registers. Any data written into the status

tion operations related to the status register may give

different results from those intended.

Bit No.

Label

Function

C is set if the operation results in a carry during an addition operation or if a borrow does not

take place during a subtraction operation; otherwise C is cleared. C is also affected by a ro-

tate through carry instruction.

1AC

AC is set if the operation results in a carry out of the low nibbles in addition or no borrow from

the high nibble into the low nibble in subtraction; otherwise AC is cleared.

Z is set if the result of an arithmetic or logic operation is zero; otherwise Z is cleared.

3OV

OV is set if the operation results in a carry into the highest-order bit but not a carry out of the

highest-order bit, or vice versa; otherwise OV is cleared.

PDF

PDF is cleared by system power-up or executing the

²CLR WDT² instruction. PDF is set by

executing the

²HALT² instruction.

5TO

TO is cleared by system power-up or executing the

²CLR WDT² or ²HALT² instruction.

TO is set by a WDT time-out.

6~7

Unused bit, read as

²0²

Status (0AH) Register

U n d e f i n e d , r e s e r v e d

f o r f u t u r e e x p a n s i o n

A W R

S T A L L

P I P E

S I E S

M I S C

F I F O 0

F I F O 1

F I F O 2

F I F O 3

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

4 B H

4 C H

F F H

RAM Bank 1

Note:

sion

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