mc9s08qd4 Freescale Semiconductor, Inc, mc9s08qd4 Datasheet - Page 143

• Manufacturer Part Number: mc9s08qd4
• Description: Hcs08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

KBISC provided all enabled keyboard inputs are at their deasserted levels. KBF will remain set if any
enabled KBI pin is asserted while attempting to clear by writing a 1 to KBACK.
10.4.3
The KBI pins can be configured to use an internal pullup/pulldown resistor using the associated I/O port
pullup enable register. If an internal resistor is enabled, the KBIES register is used to select whether the
resistor is a pullup (KBEDGn = 0) or a pulldown (KBEDGn = 1).
10.4.4
When a keyboard interrupt pin is first enabled it is possible to get a false keyboard interrupt flag. To
prevent a false interrupt request during keyboard initialization, the user must do the following:
Freescale Semiconductor
1. Mask keyboard interrupts by clearing KBIE in KBISC.
2. Enable the KBI polarity by setting the appropriate KBEDGn bits in KBIES.
3. If using internal pullup/pulldown device, configure the associated pullup enable bits in PTxPE.
4. Enable the KBI pins by setting the appropriate KBIPEn bits in KBIPE.
5. Write to KBACK in KBISC to clear any false interrupts.
6. Set KBIE in KBISC to enable interrupts.
KBI Pullup/Pulldown Resistors
KBI Initialization
MC9S08QD4 Series MCU Data Sheet, Rev. 3
Keyboard Interrupts (S08KBIV2)
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