Rev. 1.50
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Rev. 1.50
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HT66F0175/HT66F0185
A/D Flash MCU with EEPROM
HT66F0175/HT66F0185
A/D Flash MCU with EEPROM
MFI2 Register
Bit
7
6
5
4
3
2
1
0
Name
—
—
DEF
LVF
—
—
DEE
LVE
R/W
—
—
R/W
R/W
—
—
R/W
R/W
POR
—
—
0
0
—
—
0
0
Bit 7~6
Unimplemented, read as “0”
Bit 5
DEF
: Data EEPROM Interrupt request flag
0: No request
1: Interrupt request
Bit 4
LVF
: LVD Interrupt request flag
0: No request
1: Interrupt request
Bit 3~2
Unimplemented, read as “0”
Bit 1
DEE
: Data EEPROM Interrupt control
0: Disable
1: Enable
Bit 0
LVE
: LVD Interrupt control
0: Disable
1: Enable
Interrupt Operation
When the conditions for an interrupt event occur, such as a TM Comparator P or Comparator A or A/D
conversion completion, etc, the relevant interrupt request flag will be set. Whether the request flag
actually generates a program jump to the relevant interrupt vector is determined by the condition of
the interrupt enable bit. If the enable bit is set high then the program will jump to its relevant vector;
if the enable bit is zero then although the interrupt request flag is set an actual interrupt will not be
generated and the program will not jump to the relevant interrupt vector. The global interrupt enable
bit, if cleared to zero, will disable all interrupts.
When an interrupt is generated, the Program Counter, which stores the address of the next instruction
to be executed, will be transferred onto the stack. The Program Counter will then be loaded with a
new address which will be the value of the corresponding interrupt vector. The microcontroller will
then fetch its next instruction from this interrupt vector. The instruction at this vector will usually
be a JMP which will jump to another section of program which is known as the interrupt service
routine. Here is located the code to control the appropriate interrupt. The interrupt service routine
must be terminated with a RETI, which retrieves the original Program Counter address from the
stack and allows the microcontroller to continue with normal execution at the point where the
interrupt occurred.
The various interrupt enable bits, together with their associated request flags, are shown in the
accompanying diagrams with their order of priority. Some interrupt sources have their own
individual vector while others share the same multi-function interrupt vector. Once an interrupt
subroutine is serviced, all other interrupts will be blocked, as the global interrupt enable bit, EMI
bit will be cleared automatically. This will prevent any further interrupt nesting from occurring.
However, if other interrupt requests occur during this interval, although the interrupt will not be
immediately serviced, the request flag will still be recorded.