HT82K75R datasheet(10/66 Pages) HOLTEK

10 / 66 page

HT82M75R/HT82M75RE

HT82K75R/HT82K75RE

Rev. 1.10

June 11, 2010

¨ The three methods are shown as follows: The in-

structions

²TABRDC [m]² (the current page, one

page=256words), where the table location is de-

fined by TBLP (07H) in the current page. And the

configuration option TBHP is disabled (default).

¨ The instructions

²TABRDC [m]², where the table lo-

cation is defined by registers TBLP (07H) and

TBHP (01FH). And the configuration option TBHP

is enabled.

¨ The instructions

²TABRDL [m]², where the table lo-

cation is defined by register TBLP (07H) in the last

page (F00H~FFFH).

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 1-bit words are read as

²0². The Table

Higher-order byte register (TBLH) is read only. The ta-

ble pointer (TBLP, TBHP) is a read/write register (07H,

1FH), which indicates the table location. Before ac-

cessing the table, the location must be placed in the

TBLP and TBHP (If the configuration option TBHP is

disabled, the value in TBHP has no effect). The TBLH

is read only and cannot be restored. If the main rou-

tine and the ISR (Interrupt Service Routine) both em-

ploy the table read instruction, the contents of the

TBLH in the

main routine are likely to be changed by the table read

instruction 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

should be disabled prior to the table read instruction. It

will not be enabled until the TBLH has been backed

up. All table related instructions require two cycles to

complete the operation. These areas may function as

normal program memory depending on the require-

ments.

Once TBHP is enabled, the instruction

²TABRDC [m]²

reads the ROM data as defined by TBLP and TBHP

value. Otherwise, the configuration option TBHP is

disabled, the instruction

²TABRDC [m]² reads the

ROM data as defined by TBLP and the current pro-

gram counter bits.

Table Program Example

The following example shows how the table pointer and

table data is defined and retrieved from the

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

²F00H² which refers to the start address of the last page

within the 4K Program Memory of device. The table

pointer is setup here to have an initial value of

²06H².

This will ensure that the first data read from the data ta-

ble will be at the Program Memory address

²F06H² or 6

locations after the start of the last page. Note that the

value for the table pointer is referenced to the first ad-

dress of the present page if the

²TABRDC [m]² instruc-

tion 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 in-

struction is executed.

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

Table Read

- TBLP only

P r o g r a m

M e m o r y

T B L H

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

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

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

T B L P

T B H P

Table Read

- TBLP/TBHP

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