MC908AZ32ACFU Freescale Semiconductor, MC908AZ32ACFU Datasheet - Page 239

• Manufacturer Part Number: MC908AZ32ACFU
• Description: IC MCU 32K FLASH 8.4MHZ 64-QFP
• Manufacturer: Freescale Semiconductor
• Series: HC08r

Specifications of MC908AZ32ACFU

• Core Processor: HC08
• Core Size: 8-Bit
• Speed: 8MHz
• Connectivity: CAN, SCI, SPI
• Peripherals: LVD, POR, PWM
• Number Of I /o: 40
• Program Memory Size: 32KB (32K x 8)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 15x8b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-QFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

If the MODEK bit is clear, the keyboard interrupt pin is falling edge-sensitive only. With MODEK clear, a
vector fetch or software clear immediately clears the keyboard interrupt request.
Reset clears the keyboard interrupt request and the MODEK bit, clearing the interrupt request even if a
keyboard interrupt pin stays at logic 0.
The keyboard flag bit (KEYF) in the keyboard status and control register can be used to see if a pending
interrupt exists. The KEYF bit is not affected by the keyboard interrupt mask bit (IMASKK) which makes
it useful in applications where polling is preferred.
To determine the logic level on a keyboard interrupt pin, use the data direction register to configure the
pin as an input and read the data register.
22.4 Keyboard Initialization
When a keyboard interrupt pin is enabled, it takes time for the internal pullup to reach a logic 1. Therefore,
a false interrupt can occur as soon as the pin is enabled.
To prevent a false interrupt on keyboard initialization:
An interrupt signal on an edge-triggered pin can be acknowledged immediately after enabling the pin. An
interrupt signal on an edge- and level-triggered interrupt pin must be acknowledged after a delay that
depends on the external load.
Another way to avoid a false interrupt:
22.5 Low-Power Modes
The WAIT and STOP instructions put the MCU in low-power-consumption standby modes.
22.5.1 Wait Mode
The keyboard module remains active in wait mode. Clearing the IMASKK bit in the keyboard status and
control register enables keyboard interrupt requests to bring the MCU out of wait mode.
Freescale Semiconductor
1. Mask keyboard interrupts by setting the IMASKK bit in the keyboard status and control register
2. Enable the KBI pins by setting the appropriate KBIEx bits in the keyboard interrupt enable register
3. Write to the ACKK bit in the keyboard status and control register to clear any false interrupts
4. Clear the IMASKK bit.
1. Configure the keyboard pins as outputs by setting the appropriate DDRG bits in data direction
2. Configure the keyboard pins as outputs by setting the appropriate DDRH bits in data direction
3. Write logic 1s to the appropriate port G and port H data register bits.
4. Enable the KBI pins by setting the appropriate KBIEx bits in the keyboard interrupt enable register.
register G.
register H.
Setting a keyboard interrupt enable bit (KBIEx) forces the corresponding
keyboard interrupt pin to be an input, overriding the data direction register.
However, the data direction register bit must be a logic 0 for software to
read the pin.
MC68HC908AZ32A Data Sheet, Rev. 2
NOTE
Keyboard Initialization
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