HT48R065D datasheet(21/100 Pages) HOLTEK

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Table Program Example

The accompanying example shows how the table pointer and table data is defined and retrieved from

the device. This example uses raw table data located in the last page which is stored there using the

ORG statement. The value at this ORG statement is

²300H² which refers to the start address of the last

page within the 1K Program Memory of the HT48R064D microcontrollers. 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

²306H² 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.

Because the TBLH register is a read-only register and cannot be restored, care should be taken to

ensure its protection if both the main routine and Interrupt Service Routine use the table read

instructions. If using the table read instructions, the Interrupt Service Routines may change the value

of TBLH and subsequently cause errors if used again by the main routine. As a rule it is recommended

that simultaneous use of the table read instructions should be avoided. However, in situations where

simultaneous use cannot be avoided, the interrupts should be disabled prior to the execution of any

main routine table-read instructions. Note that all table related instructions require two instruction

cycles to complete their operation.

Table Read Program Example

tempreg1

db ?

; temporary register #1

tempreg2

db ?

; temporary register #2

mov

a,06h

; initialise table pointer - note that this address is referenced

mov

tblp,a

; to the last page or present page

tabrdl tempreg1

; transfers value in table referenced by table pointer

; to tempregl

; data at prog. memory address

²306H² transferred to

; tempreg1 and TBLH

dec

tblp

; reduce value of table pointer by one

Tabrdl tempreg2

; transfers value in table referenced by table pointer

; to tempreg2

; data at prog.memory address

²305H² transferred to

; tempreg2 and TBLH

; in this example the data

²1AH² is transferred to

; tempreg1 and data

²0FH² to register tempreg2

; the value

²00H² will be transferred to the high byte

; register TBLH

org

300h

; sets initial address of last page

00Ah, 00Bh, 00Ch, 00Dh, 00Eh, 00Fh, 01Ah, 01Bh

Rev. 1.00

January 12, 2011

HT48R064D/065D/066D

Enhanced I/O Type 8-Bit OTP MCU with LED Driver

HT48R065D Datasheet(PDF) 21 Page - Holtek Semiconductor Inc

HT48R065D Datasheet(HTML) 21 Page - Holtek Semiconductor Inc

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