HT46R068B/HT46R069B
Enhanced A/D Type 8-bit OTP MCU
Special Vectors
Within the Program Memory, certain locations are reserved for special usage such as reset and
interrupts.
Reset Vector
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This vector is reserved for use by the device reset for program initialisation. After a device reset
is initiated, the program will jump to this location and begin execution.
External interrupt vector
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This vector is used by the external interrupt. If the external interrupt pin on the device receives
an edge transition, the program will jump to this location and begin execution if the external
interrupt is enabled and the stack is not full. The external interrupt active edge transition type,
whether high to low, low to high or both is specified in the CTRL1 register.
Timer/Event 0/1/2 counter interrupt vector
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This internal vector is used by the Timer/Event Counters. If a Timer/Event Counter overflow
occurs, the program will jump to its respective location and begin execution if the associated
Timer/Event Counter interrupt is enabled and the stack is not full.
Multi-function interrupt vector
The Multi-function Interrupt vector is shared by several internal functions: a Time Base
overflow, an SPI/I2C or SPIA data transfer completion. The program will jump to this location
and begin execution if the relevant interrupt is enabled and the stack is not full.
Look-up Table
Any location within the Program Memory can be defined as a look-up table where programmers
can store fixed data. To use the look-up table, the table pointer must first be setup by placing the
lower order address of the look up data to be retrieved in the table pointer register, TBLP. This
register defines the lower 8-bit address of the look-up table.
After setting up the table pointer, the table data can be retrieved from the current Program Memory
page or last Program Memory page using the "TABRDC[m]" or "TABRDL[m]" instructions,
respectively. When these instructions are executed, the lower order table byte from the Program
Memory will be transferred to the user defined Data Memory register [m] as specified in the
instruction. The higher order table data byte from the Program Memory will be transferred to the
TBLH special register. Any unused bits in this transferred higher order byte will be read as "0".
The following diagram illustrates the addressing/data flow of the look-up table:
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Rev. 1.00
15
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HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
