HT46C46 datasheet(7/42 Pages) HOLTEK

7 / 42 page

HT46R46/HT46C46/HT46R47/HT46C47

Rev. 1.00

December 28, 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

´14 bits, 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 exe-

cution at location 008H.

· Location 00CH

This area is reserved for the A/D converter interrupt

service program. If an A/D converter interrupt results

from an end of A/D conversion, and if the interrupt is

enabled and the stack is not full, the program begins

execution at location 00CH.

· Table location

Any location in the ROM space 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) transfer the contents 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 table is well-defined, the

other bits of the table word are transferred to the lower

portion of TBLH, and the remaining 2 bits are read as

²0². The Table Higher-order byte register (TBLH) is

read only. The table pointer (TBLP) is a read/write reg-

ister (07H), which indicates the table location. Before

accessing the table, the location must be placed in

TBLP. The TBLH is read only and cannot be restored.

If the main routine and the ISR (Interrupt Service Rou-

tine) both employ the table read instruction, the con-

tents of the TBLH in the main routine are likely to be

changed by the table read instruction used in the ISR.

1 4 b i t s

n 0 0 H

n F F H

P r o g r a m

M e m o r y

D e v i c e I n i t i a l i z a t i o n P r o g r a m

E x t e r n a l I n t e r r u p t S u b r o u t i n e

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 S u b r o u t i n e

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

N o t e : n r a n g e s f r o m 0 t o 3

0 0 0 H

0 0 4 H

0 0 8 H

A / D C o n v e r t e r I n t e r r u p t S u b r o u t i n e

0 0 C H

3 F F H

3 0 0 H

Program Memory for the HT46R46/HT46C46

Instruction

Table Location

*10

TABRDC [m]

P10

TABRDL [m]

Table Location

Note:

*10~*0: Table location bits

P10~P8: Current program counter bits

@7~@0: Table pointer bits

For the HT46R47/HT46C47, the Table address location is 11 bits, i.e. from *10~*0.

For the HT46R46/HT46C46, the Table address location is 10 bits, i.e. from *9~*0.

1 4 b i t s

n 0 0 H

n F F H

P r o g r a m

M e m o r y

D e v i c e I n i t i a l i z a t i o n P r o g r a m

E x t e r n a l I n t e r r u p t S u b r o u t i n e

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 S u b r o u t i n e

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

N o t e : n r a n g e s f r o m 0 t o 7

0 0 0 H

0 0 4 H

0 0 8 H

A / D C o n v e r t e r I n t e r r u p t S u b r o u t i n e

0 0 C H

7 F F H

7 0 0 H

Program Memory for the HT46R47/HT46C47

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