MC68HC705J MOTOROLA [Motorola, Inc], MC68HC705J Datasheet - Page 76

• Manufacturer Part Number: MC68HC705J
• Description: Microcontrollers
• Manufacturer: MOTOROLA [Motorola, Inc]

Resets and Interrupts
4.4.3 Timer Interrupts
4.4.3.1 Real-Time Interrupt
4.4.3.2 Timer Overflow Interrupt
4.4.4 Interrupt Processing
Technical Data
76
The timer can generate these interrupt requests:
Setting the I bit in the condition code register disables timer interrupts.
A real-time interrupt occurs if the real-time interrupt flag, RTIF, becomes
set while the real-time interrupt enable bit, RTIE, is also set. RTIF and
RTIE are in the timer status and control register.
A timer overflow interrupt request occurs if the timer overflow flag, TOF,
becomes set while the timer overflow interrupt enable bit, TOIE, is also
set. TOF and TOIE are in the timer status and control register.
The CPU takes these actions to begin servicing an interrupt:
The return-from-interrupt (RTI) instruction causes the CPU to recover
the CPU registers from the stack as shown in
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•
•
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Real time
Timer overflow
Stores the CPU registers on the stack in the order shown in
Figure 4-6
Sets the I bit in the condition code register to prevent further
interrupts
Loads the program counter with the contents of the appropriate
interrupt vector locations:
– $07FC and $07FD (software interrupt vector)
– $07FA and $07FB (external interrupt vector)
– $07F8 and $07F9 (timer interrupt vector)
Resets and Interrupts
Figure
MC68HC705J1A — Rev. 4.0
4-6.
MOTOROLA