Rev. 1.00
18
March 24, 2020
Rev. 1.00
19
March 24, 2020
BS83A04C
4-Key Enhanced Touch I/O Flash MCU
BS83A04C
4-Key Enhanced Touch I/O Flash MCU
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 located in the Program Memory which is
stored there using the ORG statement. The value at this ORG statement is “0300H” which refers to
the start address of the last page within the 1K 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 “0306H” or 6 locations after
the start of the last page. Note that the value for the table pointer is referenced to the first address
specified by TBLP and TBHP if the “TABRD [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 “TABRD [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 ; initialise low table pointer - note that this address is referenced
mov tblp,a ; to the last page or the page that tbhp pointed
mov a,03h ; initialise high table pointer
mov tbhp,a
:
:
tabrd tempreg1 ; transfers value in table referenced by table pointer data at program
; memory address “0306H” transferred to tempreg1 and TBLH
dec tblp ; reduce value of table pointer by one
tabrd tempreg2 ; transfers value in table referenced by table pointer
; data at program memory address “0305H” transferred to tempreg2 and
; TBLH in this example the data “1AH” is transferred to tempreg1 and
;
data
“0FH”
to
register
tempreg2
:
:
org 0300h ; sets initial address of program memory
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.
