MC68HC908AP8CB Freescale Semiconductor, MC68HC908AP8CB Datasheet - Page 275

• Manufacturer Part Number: MC68HC908AP8CB
• Description: IC MCU 8K FLASH 8MHZ 42SDIP
• Manufacturer: Freescale Semiconductor
• Series: HC08r

Specifications of MC68HC908AP8CB

• Core Processor: HC08
• Core Size: 8-Bit
• Speed: 8MHz
• Connectivity: I²C, IRSCI, SCI, SPI
• Peripherals: LED, LVD, POR, PWM
• Number Of I /o: 32
• Program Memory Size: 8KB (8K x 8)
• Program Memory Type: FLASH
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 42-DIP (0.600", 15.24mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -

17.4 IRQ1 and IRQ2 Pins
A logic 0 on the IRQ pin can latch an interrupt request into the IRQ latch. A vector fetch, software clear,
or reset clears the IRQ latch.
If the MODE bit is set, the IRQ pin is both falling-edge-sensitive and low-level-sensitive. With MODE set,
both of the following actions must occur to clear IRQ:
The vector fetch or software clear and the return of the IRQ pin to logic 1 may occur in any order. The
interrupt request remains pending as long as the IRQ pin is at logic 0. A reset will clear the latch and the
MODE control bit, thereby clearing the interrupt even if the pin stays low.
If the MODE bit is clear, the IRQ pin is falling-edge-sensitive only. With MODE clear, a vector fetch or
software clear immediately clears the IRQ latch.
The IRQF bit in the INTSCR register can be used to check for pending interrupts. The IRQF bit is not
affected by the IMASK bit, which makes it useful in applications where polling is preferred.
Use the BIH or BIL instruction to read the logic level on the IRQ1 pin.
Freescale Semiconductor
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Vector fetch or software clear — A vector fetch generates an interrupt acknowledge signal to clear
the latch. Software may generate the interrupt acknowledge signal by writing a logic 1 to the ACK
bit in the interrupt status and control register (INTSCR). The ACK bit is useful in applications that
poll the IRQ pin and require software to clear the IRQ latch. Writing to the ACK bit prior to leaving
an interrupt service routine can also prevent spurious interrupts due to noise. Setting ACK does
not affect subsequent transitions on the IRQ pin. A falling edge that occurs after writing to the ACK
bit another interrupt request. If the IRQ mask bit, IMASK, is clear, the CPU loads the program
counter with the vector address at location defined in
Return of the IRQ pin to logic 1 — As long as the IRQ pin is at logic 0, IRQ remains active.
IRQ2
V
DD
The BIH and BIL instructions do not read the logic level on the IRQ2 pin.
INTERNAL
PULLUP
DEVICE
DECODER
VECTOR
FETCH
RESET
ACK2
PUC0ENB
V
MODE2
MC68HC908AP Family Data Sheet, Rev. 4
DD
Figure 17-3. IRQ2 Block Diagram
D
CK
CLR
Q
NOTE
IMASK2
Table 2-1 . Vector
SYNCHRONIZER
Addresses.
IRQ2F
IRQ1 and IRQ2 Pins
IRQ2
INTERRUPT
REQUEST
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