HT48C062 Ver la hoja de datos (PDF) - Holtek Semiconductor

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HT48C062

Cost-Effective I/O Type 8-Bit MCU

Holtek Semiconductor 

HT48R062/HT48C062

Program Memory - ROM

The program memory is used to store the program in-

structions which are to be executed. It also contains

data and table and is organized into 1024´14 bits, ad-

dressed by the program counter and table pointer.

Certain locations in the program memory are reserved

for special usage:

· Location 000H

This area is reserved for the initialization program. Af-

ter chip reset, the program always begins execution at

location 000H.

· Table location

Any location in the EPROM space can be used as

look-up tables. The instructions ²TABRDC [m]² (the

current page, one page=256 words) and ²TABRDL

[m]² (the last page) transfer the contents of the

lower-order byte to the specified data memory, and

the higher-order byte to TBLH (08H). Only the desti-

nation of the lower-order byte in the table is

well-defined, the other bits of the table word are trans-

ferred to the lower portion of TBLH, the remaining 2

bits are read as ²0². The Table Higher-order byte reg-

ister (TBLH) is read only. The table pointer (TBLP) is a

read/write register (07H), where P indicates the table

location. Before accessing the table, the location must

be placed in TBLP. The TBLH is read only and cannot

be restored. All table related instructions need 2 cy-

cles to complete the operation. These areas may

function as normal program memory depending upon

the requirements.

000H

D e v ic e in itia liz a tio n p r o g r a m

n00H

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

nFFH

P ro g ra m

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

3FFH

1 4 b its

N o te : n ra n g e s fro m 0 to 3

Program Memory

Stack Register - STACK

This is a special part of the memory used to save the

contents of the Program Counter only. The stack is orga-

nized into one level and is neither part of the data nor

part of the program space, and is neither readable nor

writeable. The activated level is indexed by the stack

pointer (SP) and is neither readable nor writeable. At a

subroutine call the contents of the program counter are

pushed onto the stack. At the end of a subroutine sig-

naled by a return instruction (RET), the program counter

is restored to its previous value from the stack. After a

chip reset, the SP will point to the top of the stack.

If the stack is full and a ²CALL² is subsequently exe-

cuted, stack overflow occurs and the first entry will be

lost (only the most recent return address is stored).

Data Memory - RAM

The data memory is designed with 44´8 bits. The data

memory is divided into two functional groups: special

function registers and general purpose data memory

(32´8). Most of them are read/write, but some are read

only.

The special function registers include the Indirect Ad-

dressing Register (00H), the Memory Pointer register

(MP;01H), the Accumulator (ACC;05H) the Program

Counter Lower-order byte register (PCL;06H), the Table

Pointer (TBLP;07H), the table higher-order byte register

(TBLH;08H), the Watchdog Timer option setting register

(WDTS;09H), the STATUS register (STATUS;0AH), the

I/O registers (PA;12H, PB;14H) and I/O control registers

(PAC;13H, PBC;15H). The remaining space before the

20H is reserved for future expanded usage and reading

these locations will return the result 00H. The general

purpose data memory, addressed from 20H to 3FH, is

used for data and control information under instruction

command.

All data memory areas can handle arithmetic, logic, in-

crement, decrement and rotate operations directly. Ex-

cept for some dedicated bits, each bit in the data

memory can be set and reset by the ²SET [m].i² and

²CLR [m].i² instructions, respectively. They are also indi-

rectly accessible through memory pointer register

(MP;01H).

Instruction(s)

TABRDC [m]

TABRDL [m]

Table Location

*9

*8

*7

*6

*5

*4

*3

*2

*1

*0

P9

P8

@7 @6 @5 @4 @3 @2 @1 @0

1

1

@7 @6 @5 @4 @3 @2 @1 @0

Note: *9~*0: Table location bits

P9~P8: Current program counter bits

Table Location

@7~@0: Table pointer bits

Rev. 1.21

5

December 30, 2008

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