HT46R01A datasheet(8/58 Pages) HOLTEK

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HT46R01A

Rev. 1.10

August 13, 2008

Arithmetic and Logic Unit

- ALU

The arithmetic-logic unit or ALU is a critical area of the

microcontroller that carries out arithmetic and logic op-

erations of the instruction set. Connected to the main

microcontroller data bus, the ALU receives related in-

struction codes and performs the required arithmetic or

logical operations after which the result will be placed in

the specified register. As these ALU calculation or oper-

ations may result in carry, borrow or other status

changes, the status register will be correspondingly up-

dated to reflect these changes. The ALU supports the

following functions:

· Arithmetic operations: ADD, ADDM, ADC, ADCM,

SUB, SUBM, SBC, SBCM, DAA

· Logic operations: AND, OR, XOR, ANDM, ORM,

XORM, CPL, CPLA

· Rotation RRA, RR, RRCA, RRC, RLA, RL, RLCA,

RLC

· Increment and Decrement INCA, INC, DECA, DEC

· Branch decision, JMP, SZ, SZA, SNZ, SIZ, SDZ,

SIZA, SDZA, CALL, RET, RETI

Program Memory

The Program Memory is the location where the user

code or program is stored. These devices are supplied

with One-Time Programmable, OTP, memory where us-

ers can program their application code into the device.

By using the appropriate programming tools, OTP de-

vices offer users the flexibility to freely develop their ap-

plications which may be useful during debug or for

products requiring frequent upgrades or program

changes. OTP devices are also applicable for use in ap-

plications that require low or medium volume production

runs.

Structure

The Program Memory has a capacity of 1K by 14. The

Program Memory is addressed by the Program Counter

and also contains data, table information and interrupt

entries. Table data, which can be setup in any location

within the Program Memory, is addressed by separate

table pointer registers.

Special Vectors

Within the Program Memory, certain locations are re-

served for special usage such as reset and interrupts.

· Location 000H

This vector is reserved for use by the device reset for

program initialisation. After a device reset is initiated, the

program will jump to this location and begin execution.

· Location 004H

This vector is used by the external interrupt. If the ex-

ternal interrupt pin on the device receives an edge

transition, the program will jump to this location and

begin execution if the external interrupt is enabled and

the stack is not full. The external interrupt active edge

transition type, whether high to low, low to high or both

is specified in the CTRL1 register.

· Location 008H

This internal vector is used by the Timer/Event Coun-

ter. If a counter overflow occurs, the program will jump

to this location and begin execution if the timer/event

counter interrupt is enabled and the stack is not full.

· Location 00CH

This internal vector is used by the A/D converter.

When an A/D conversion cycle is complete, the pro-

gram will jump to this location and begin execution if

the A/D interrupt is enabled and the stack is not full.

Look-up Table

Any location within the Program Memory can be defined

as a look-up table where programmers can store fixed

data. To use the look-up table, the table pointer must

first be setup by placing the lower order address of the

look up data to be retrieved in the table pointer register,

TBLP. This register defines the lower 8-bit address of

the look-up table.

After setting up the table pointer, the table data can be

retrieved from the current Program Memory page or last

Program Memory page using the

²TABRDC[m]² or

²TABRDL [m]² instructions, respectively. When these in-

structions are executed, the lower order table byte from

the Program Memory will be transferred to the user de-

fined Data Memory register [m] as specified in the in-

struction. The higher order table data byte from the

Program Memory will be transferred to the TBLH special

byte will be read as

²0².

3 F F H

1 4 b i t s

0 1 4 H

I n i t i a l i s a t i o n

V e c t o r

E x t e r n a l

I n t e r r u p t V e c t o r

T i m e r / E v e n t C o u n t e r

I n t e r r u p t V e c t o r

A / D C o n v e r t e r

I n t e r r u p t V e c t o r

0 0 0 H

0 0 4 H

0 0 8 H

0 0 C H

0 1 0 H

3 0 0 H

Program Memory Structure

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