HT48C06 datasheet(6/38 Pages) HOLTEK

6 / 38 page

HT48R05A-1/HT48C05/HT48R06A-1/HT48C06

Rev. 1.10

June 9, 2004

Program Memory

- ROM

The program memory is used to store the program in-

structions which are to be executed. It also contains

data, table, and interrupt entries, and is organized into

512

´14 bits (HT48R05A-1/HT48C05) or 1024´14 bits

(HT48R06A-1/HT48C06), addressed 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 program initialization. After

chip reset, the program always begins execution at lo-

cation 000H.

· Location 004H

This area is reserved for the external interrupt service

program. If the INT input pin is activated, the interrupt

is enabled and the stack is not full, the program begins

execution at location 004H.

· Location 008H

This area is reserved for the timer/event counter inter-

rupt service program. If a timer interrupt results from a

timer/event counter overflow, and if the interrupt is en-

abled and the stack is not full, the program begins ex-

ecution at location 008H.

· Table location

Any location in the program memory can be used as

look-up tables. The instructions

²TABRDC [m]² (the

current page, 1 page=256 words) and

²TABRDL [m]²

(the last page; However this statement is not valid for

the HT48R05A-1/HT48C05 devices) transfer the con-

tents of the lower-order byte to the specified data

memory, and the higher-order byte to TBLH (08H).

Only the destination of the lower-order byte in the ta-

ble is well-defined, the other bits of the table word are

transferred to the lower portion of TBLH, and the re-

maining 2 bits are read as

²0². The Table Higher-order

byte register (TBLH) is read only. The table pointer

(TBLP) is a read/write register (07H), which indicates

the table location. Before accessing the table, the lo-

cation must be placed in TBLP. The TBLH is read only

and cannot be restored. If the main routine and the

ISR (Interrupt Service Routine) both employ the table

read instruction, the contents of the TBLH in the main

routine are likely to be changed by the table read in-

struction used in the ISR. Errors can occur. In other

words, using the table read instruction in the main rou-

tine and the ISR simultaneously should be avoided.

However, if the table read instruction has to be applied

in both the main routine and the ISR, the interrupt is

supposed to be disabled prior to the table read in-

N o t I m p l e m e n t e d

1 F F H

2 0 0 H

3 F F H

I n i t i a l i z 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 / C o u n t e r

I n t e r r u p t 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 / C o u n t e r

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

I n i t i a l i z a t i o n

V e c t o r

0 0 8 H

H T 4 8 R 0 5 A - 1 / H T 4 8 C 0 5

1 4 b i t s

0 0 0 H

0 0 4 H

H T 4 8 R 0 6 A - 1 / H T 4 8 C 0 6

Program Memory

Instruction

Table Location

TABRDC [m]

TABRDL [m]

Table Location

Note: *9~*0: Table location bits

P9, P8: Current program counter bits

@7~@0: Table pointer bits

For HT48R05A-1/HT48C05, the table address location is 9 bits, i.e. from *8~*0

For HT48R06A-1/HT48C06, the table address location is 10 bits, i.e. from *9~*0

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