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MC68HC908JB8 Datasheet, PDF (224/286 Pages) Motorola, Inc – MICROCONTROLLERS | |||
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External Interrupt (IRQ)
13.8 IRQ Status and Control Register
The IRQ status and control register (ISCR) controls and monitors
operation of the IRQ module. The ISCR has the following functions:
⢠Shows the state of the IRQ flag
⢠Clears the IRQ latch
⢠Masks IRQ interrupt request
⢠Controls triggering sensitivity of the IRQ pin
Address: $001E
Bit 7
6
5
4
3
2
1
Bit 0
Read: 0
0
0
0
IRQF
0
IMASK MODE
Write:
ACK
Reset: 0
0
0
0
0
0
0
0
= Unimplemented
Figure 13-3. IRQ Status and Control Register (ISCR)
IRQF â IRQ Flag
This read-only status bit is high when the IRQ interrupt is pending.
1 = IRQ interrupt pending
0 = IRQ interrupt not pending
ACK â IRQ Interrupt Request Acknowledge Bit
Writing a logic 1 to this write-only bit clears the IRQ latch. ACK always
reads as logic 0. Reset clears ACK.
IMASK â IRQ Interrupt Mask Bit
Writing a logic 1 to this read/write bit disables IRQ interrupt requests.
Reset clears IMASK.
1 = IRQ interrupt requests disabled
0 = IRQ interrupt requests enabled
MODE â IRQ Edge/Level Select Bit
This read/write bit controls the triggering sensitivity of the IRQ pin.
Reset clears MODE.
1 = IRQ interrupt requests on falling edges and low levels
Technical Data
224
MC68HC908JB8â¢MC68HC08JB8â¢MC68HC08JT8 â Rev. 2.3
External Interrupt (IRQ)
Freescale Semiconductor
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