Rev. 2.10
208
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Rev. 2.10
209
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HT68F20/HT68F30/HT68F40/HT68F50/HT68F60
HT68FU30/HT68FU40/HT68FU50/HT68FU60
Enhanced I/O Flash Type 8-Bit MCU with EEPROM
HT68F20/HT68F30/HT68F40/HT68F50/HT68F60
HT68FU30/HT68FU40/HT68FU50/HT68FU60
Enhanced I/O Flash Type 8-Bit MCU with EEPROM
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.
TM Interrupts
The Compact and Standard Type TMs have two interrupts each, while the Enhanced Type TM has
three interrupts. All of the TM interrupts are contained within the Multi-function Interrupts. For each
of the Compact and Standard Type TMs there are two interrupt request flags TnPF and TnAF and
two enable bits TnPE and TnAE. For the Enhanced Type TM there are three interrupt request flags
TnPF, TnAF and TnBF and three enable bits TnPE, TnAE and TnBE. 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, A or B match situation happens.
To allow the program to branch to its respective interrupt vector address, the global interrupt enable
bit, EMI, respective TM Interrupt enable bit, and relevant Multi-function Interrupt enable bit, MFnE,
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 Multi-function 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.
Interrupt Wake-up Function
Each of the interrupt functions has the capability of waking up the microcontroller when in the
SLEEP or IDLE Mode. A wake-up is generated when an interrupt request flag changes from low to
high and is independent of whether the interrupt is enabled or not. Therefore, even though the device
is in the SLEEP or IDLE Mode and its system oscillator stopped, situations such as external edge
transitions on the external interrupt pins, a low power supply voltage or comparator input change
may cause their respective interrupt flag to be set high and consequently generate an interrupt. Care
must therefore be taken if spurious wake-up situations are to be avoided. If an interrupt wake-up
function is to be disabled then the corresponding interrupt request flag should be set high before the
device enters the SLEEP or IDLE Mode. The interrupt enable bits have no effect on the interrupt
wake-up function.