HT46R46 datasheet(11/77 Pages) HOLTEK

11 / 77 page

HT46R46/C46/R47/C47/R48A/C48A/R49

Rev. 1.30

June 5, 2008

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

byte will be read as

²0².

The following diagram illustrates the addressing/data

flow of the look-up table:

Table Program Example

The following example shows how the table pointer and

table data is defined and retrieved from the HT46R47

microcontroller. This example uses raw table data lo-

cated in the last page which is stored there using the

ORG statement. The value at this ORG statement is

²700H² which refers to the start address of the last page

within the 2K Program Memory of the HT46R47

microcontroller. The table pointer is setup here to have

an initial value of

²06H². This will ensure that the first

data read from the data table will be at the Program

Memory address

²706H² or 6 locations after the start of

the last page. Note that the value for the table pointer is

referenced to the first address of the present page if the

²TABRDC [m]² instruction is being used. The high byte

of the table data which in this case is equal to zero will

be transferred to the TBLH register automatically when

the

²TABRDL [m]² instruction is executed.

3 F F H

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

1 5 b i t s

1 4 b i t s

8 0 0 H

F F F H

0 1 4 H

I n i t i a l i s 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

I n i t i a l i s 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 / E v e n t 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 s 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 / E v e n t C o u n t e r

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

H T 4 6 R 4 7

H T 4 6 R 4 8 A

H T 4 6 R 4 9

H T 4 6 R 4 6

A / D C o n v e r t e r

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

A / D C o n v e r t e r

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

A / D C o n v e r t e r

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

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 V e c t o r

0 0 0 H

0 0 4 H

0 0 8 H

0 0 C H

0 1 0 H

3 0 0 H

7 F F H

4 0 0 H

Program Memory Structure

P r o g r a m

M e m o r y

P r o g r a m C o u n t e r

H i g h B y t e

T B L P

T B L H

S p e c i f i e d b y [ m ]

T a b l e C o n t e n t s H i g h B y t e

T a b l e C o n t e n t s L o w B y t e

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