HT46R068B/HT46R069B
Enhanced A/D Type 8-bit OTP MCU
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 "7F00H" which refers to the start
address of the last page within the 32K Program Memory of the microcontrollers. The table pointer
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 "7F06H" 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 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 Location
Instruction(s)
b14 b13 b12 b11 b10 b9 b8 b7 b6 b5 b4 b3 b2 b1 b0
TABRDC [m] PC14 PC13 PC1ꢃ PC11 PC10 PC9 PC8 @7 @ꢄ @5 @4 @3 @ꢃ @1 @0
TABRDL [m]
1
1
1
1
1
1
1
@7 @ꢄ @5 @4 @3 @ꢃ @1 @0
Note: PC14~PC8: Current Program Counter bits
@7~@0: Table Pointer TBLP bits
For the HT46R068B, the Table address location is 14 bits, i.e. from b13~b0
For the HT46R069B, the Table address location is 15 bits, i.e. from b14~b0
Rev. 1.00
1ꢄ
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