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Rev. 1.21
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HT66F488/HT66F489
A/D Flash MCU with EEPROM
HT66F488/HT66F489
A/D Flash MCU with EEPROM
EEPROM Interrupt
An EEPROM Interrupt request will take place when the EEPROM Interrupt request flag, DEF, is set,
which occurs when an EEPROM Write cycle ends. To allow the program to branch to its respective
interrupt vector address, the global interrupt enable bit, EMI, and EEPROM Interrupt enable bit,
DEE, must first be set. When the interrupt is enabled, the stack is not full and an EEPROM Write
cycle ends, a subroutine call to the respective EEPROM Interrupt vector, will take place. When the
EEPROM Interrupt is serviced, the EMI bit will be automatically cleared to disable other interrupts,
and the EEPROM interrupt request flag, DEF, will also be automatically cleared.
TM Interrupts
The Compact, Standard and Periodic Type TMs each has two interrupts. All of the TM interrupts
are contained within the Multi-function Interrupts. For each of the Compact, Standard and Periodic
Type TMs there are two interrupt request flags xTMnPF and xTMnAF and two enable bits xTMnPE
and xTMnAE. A TM interrupt request will take place when any of the TM request flags are set, a
situation which occurs when a TM comparator P or comparator A match situation happens.
To allow the program to branch to its respective interrupt vector address, the global interrupt enable
bit, EMI, and the respective TM Interrupt enable bit, and associated Multi-function interrupt enable
bit, MFnF, must first be set. When the interrupt is enabled, the stack is not full and a TM comparator
match situation occurs, a subroutine call to the relevant TM Interrupt vector locations, will take
place. When the TM interrupt is serviced, the EMI bit will be automatically cleared to disable other
interrupts, however only the related MFnF flag will be automatically cleared. As the TM interrupt
request flags will not be automatically cleared, they have to be cleared by the application program.
LVD Interrupt
The Low Voltage Detector Interrupt is contained within the Multi-function Interrupt. An LVD
Interrupt request will take place when the LVD Interrupt request flag, LVF, is set, which occurs
when the Low Voltage Detector function detects a low power supply voltage. To allow the program
to branch to its respective interrupt vector address, the global interrupt enable bit, EMI, Low Voltage
Interrupt enable bit, LVE, and associated Multi-function interrupt enable bit, must first be set. When
the interrupt is enabled, the stack is not full and a low voltage condition occurs, a subroutine call to
the Multi-function Interrupt vector will take place. When the Low Voltage Interrupt is serviced, the
EMI bit will be automatically cleared to disable other interrupts, however only the Multi-function
interrupt request flag will be also automatically cleared. As the LVF flag will not be automatically
cleared, it has to be cleared by the application program.
UART Interrupt
Several individual UART conditions can generate a UART interrupt. When these conditions exist,
a low pulse will be generated to get the attention of the microcontroller. These conditions are a
transmitter data register empty, transmitter idle, receiver data available, receiver overrun, address
detect and an RX pin wake-up. To allow the program to branch to the respective interrupt vector
addresses, the global interrupt enable bit, EMI, and UART interrupt enable bit, UARE, must first
be set. When the interrupt is enabled, the stack is not full and any of these conditions are created,
a subroutine call to the UART Interrupt vector will take place. When the interrupt is serviced, the
UART Interrupt flag, UARF, will be automatically cleared. The EMI bit will also be automatically
cleared to disable other interrupts. However, the USR register flags will be cleared automatically
when certain actions are taken by the UART, the details of which are given in the UART section.