HT46R4A 데이터 시트보기 (PDF) - Holtek Semiconductor

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HT46R4A

Cost-Effective A/D Type 8-Bit MCU

Holtek Semiconductor 

HT46R4A

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. For this device, the type of memory

is One-Time Programmable, OTP, memory where users

can program their application code into the device. By us-

ing the appropriate programming tools, OTP devices of-

fer users the flexibility to freely develop their applications

which may be useful during debug or for products requir-

ing frequent upgrades or program changes. OTP devices

are also applicable for use in applications that require low

or medium volume production runs.

Structure

The Program Memory has a capacity of 4K by 15 bits.

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 goes low, the pro-

gram will jump to this location and begin execution if

the external interrupt is enabled and the stack is not

full.

· Location 008H

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

ter 0. 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 Timer/Event Coun-

ter 1. 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 010H

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.

000H

In itia lis a tio n V e c to r

004H

E x te rn a l In te rru p t V e c to r

008H

T im e r /E v e n t C o u n te r 0 In te r r u p t V e c to r

00C H

T im e r /E v e n t C o u n te r 1 In te r r u p t V e c to r

010H

A /D C o n v e r te r In te r r u p t S u b r o u tin e

P ro g ra m

M e m o ry

n00H

L o o k - u p T a b le ( 2 5 6 w o r d s )

nFFH

F00H

L o o k - u p T a b le ( 2 5 6 w o r d s )

FFFH

1 5 b its

N o te : n ra n g e s fro m 0 to F

Program Memory Structure

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

register. Any unused bits in this transferred higher order

byte will be read as ²0².

Rev. 1.00

8

November 28, 2007

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