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HT46R003B
Cost-Effective A/D 8-bit OTP MCU
HT46R003B
Cost-Effective A/D 8-bit OTP MCU
Once an interrupt subroutine is serviced, all the other interrupts will be blocked, as the 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. If an interrupt requires immediate servicing while the
program is already in another interrupt service routine, the EMI bit should be set after entering the
routine, to allow interrupt nesting. If the stack is full, the interrupt request will not be acknowledged,
even if the related interrupt is enabled, until the Stack Pointer is decremented. If immediate service
is desired, the stack must be prevented from becoming full.
When an interrupt request is generated it takes 2 or 3 instruction cycles before the program jumps to
the interrupt vector. If the device is in the Sleep Mode and is woken up by an interrupt request then
it will take 3 cycles before the program jumps to the interrupt vector.
Main
Program
Enable bit set?
Main
Program
Automatically Disable Interrupt
Clear EMI & Request Flag
Wait for 2~3 Instruction Cycles
ISR Entry
...
...
RETI
(it will set EMI automatically)
Interrupt Request or
Interrupt Flag Set by Instruction
N
Y
Interrupt Flow
Interrupt Priority
Interrupts, occurring in the interval between the rising edges of two consecutive T2 pulses, will be
serviced on the latter of the two T2 pulses, if the corresponding interrupts are enabled. In case of
simultaneous requests, the following table shows the priority that is applied. These can be masked
by resetting the EMI bit.
Interrupt Source
Priority
Vector
External interr�pt
1
0�H
Timer/Event Counter overflow
�
08H
A/D converter complete
3
0CH
Time Base Overflow
�
10H