Rev. 1.00
24
August 29, 2018
Rev. 1.00
25
August 29, 2018
HT45F6530
AC Voltage Regulator Flash MCU
HT45F6530
AC Voltage Regulator Flash MCU
address of the last page within the 2K Program Memory of the microcontroller. The table pointer low
byte register is setup here to have an initial value of “06H”. This will ensure that the first data read
from the data table will be at the Program Memory address “0706H” 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 “TABRDC [m]” 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 “TABRDL [m]”
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 table read
instructions. If using the table read instructions, the Interrupt Service Routines may change the
value of the 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 ; initialize 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 tempreg1
;
data
at
program
memory
address
“0706H”
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
program
memory
address
“0705H”
transferred
to
;
tempreg2
and
TBLH
; in this example the data “1AH” is transferred to
;
tempreg1
and
data
“0FH”
to
register
tempreg2
; the value “00H” will be transferred to the high byte
;
register
TBLH
:
org 0700h ; sets initial address of last page
dc 00Ah, 00Bh, 00Ch, 00Dh, 00Eh, 00Fh, 01Ah, 01Bh
:
In Circuit Programming – ICP
The provision of Flash type Program Memory provides the user with a means of convenient and
easy upgrades and modifications to their programs on the same device.
As an additional convenience, Holtek has provided a means of programming the microcontroller in-
circuit using a 4-pin interface. This provides manufacturers with the possibility of manufacturing
their circuit boards complete with a programmed or un-programmed microcontroller, and then
programming or upgrading the program at a later stage. This enables product manufacturers to easily
keep their manufactured products supplied with the latest program releases without removal and re-
insertion of the device.
