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HT66F0175/HT66F0185
A/D Flash MCU with EEPROM
HT66F0175/HT66F0185
A/D Flash MCU with EEPROM
External Interrupt
The external interrupts are controlled by signal transitions on the pins INT0~INT1. An external
interrupt request will take place when the external interrupt request flags, INT0F~INT1F, are set,
which will occur when a transition, whose type is chosen by the edge select bits, appears on the
external interrupt pins. To allow the program to branch to its respective interrupt vector address,
the global interrupt enable bit, EMI, and respective external interrupt enable bit, INT0E~INT1E,
must first be set. Additionally the correct interrupt edge type must be selected using the INTEG
register to enable the external interrupt function and to choose the trigger edge type. As the external
interrupt pins are pin-shared with I/O pins, they can only be configured as external interrupt pins if
their external interrupt enable bit in the corresponding interrupt register has been set and the external
interrupt pin is selected by the corresponding pin-shared function selection bits. The pin must also
be setup as an input by setting the corresponding bit in the port control register. When the interrupt
is enabled, the stack is not full and the correct transition type appears on the external interrupt pin,
a subroutine call to the external interrupt vector, will take place. When the interrupt is serviced, the
external interrupt request flags, INT0F~INT1F, will be automatically reset and the EMI bit will be
automatically cleared to disable other interrupts. Note that any pull-high resistor selections on the
external interrupt pins will remain valid even if the pin is used as an external interrupt input.
The INTEG register is used to select the type of active edge that will trigger the external interrupt.
A choice of either rising or falling or both edge types can be chosen to trigger an external interrupt.
Note that the INTEG register can also be used to disable the external interrupt function.
Comparator Interrupt – HT66F0185
The comparator interrupt is controlled by the internal comparator. A comparator interrupt request
will take place when the comparator interrupt request flag, CPF, is set, a situation that will occur
when the comparator output changes state. To allow the program to branch to its respective interrupt
vector address, the global interrupt enable bit, EMI, and comparator interrupt enable bit, CPE, must
first be set. When the interrupt is enabled, the stack is not full and the comparator inputs generate
a comparator output transition, a subroutine call to the comparator interrupt vector, will take place.
When the interrupt is serviced, the comparator interrupt request flag, will be automatically reset and
the EMI bit will be automatically cleared to disable other interrupts.
Multi-function Interrupt
Within the device there are up to three Multi-function interrupts. Unlike the other independent
interrupts, these interrupts have no independent source, but rather are formed from other existing
interrupt sources, namely the TM interrupts, LVD interrupt and EEPROM write operation interrupt.
A Multi-function interrupt request will take place when any of the Multi-function interrupt request
flags MFnF are set. The Multi-function interrupt flags will be set when any of their included
functions generate an interrupt request flag. To allow the program to branch to its respective interrupt
vector address, when the Multi-function interrupt is enabled and the stack is not full, and either one
of the interrupts contained within each of Multi-function interrupt occurs, a subroutine call to one of
the Multi-function interrupt vectors will take place. When the interrupt is serviced, the related Multi-
Function request flag will be automatically reset and the EMI bit will be automatically cleared to
disable other interrupts.
However, it must be noted that, although the Multi-function Interrupt request flags will be
automatically reset when the interrupt is serviced, the request flags from the original source of
the Multi-function interrupts will not be automatically reset and must be manually reset by the
application program.