HT45F4M View Datasheet(PDF) - Holtek Semiconductor

Part Name

Description

Manufacturer

HT45F4M

Lithium Battery Backup Power ASSP MCU

Holtek Semiconductor 

HT45F4M

Lithium Battery Backup Power ASSP MCU

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 address

of the look up data to be retrieved in the table pointer register, TBLP and TBHP. These registers

define the total address of the look-up table.

After setting up the table pointer, the table data can be retrieved from the Program Memory using

the “TABRD [m]” or “TABRDL[m]” instructions, respectively. When the instruction is executed,

the lower order table byte from the Program Memory will be transferred to the user defined

Data Memory register [m] as specified in the instruction. 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 “0”.

The accompanying diagram illustrates the addressing data flow of the look-up table.

Lastpage or

T B H P R e g is te r

T B L P R e g is te r

P ro g ra m M e m o ry

D a ta

1 6 b its

R e g is te r T B L H

H ig h B y te

U s e r S e le c te d

R e g is te r

L o w B y te

Table Location Bits

Instruction

b10 b9 b8 b7 b6 b5 b4 b3 b2 b1 b0

TABRD [m] @10 @9 @8 @7 @6 @5 @4 @3 @2 @1 @0

TABRDL [m] 1

1

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

Table Location

Note: b10~b0: Table location bits

@7~@0: Table pointer (TBLP) bits

@10~@8: Table pointer (TBHP) bits

Rev. 1.10

18

January 15, 2013

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