MC9S08GT16 MOTOROLA [Motorola, Inc], MC9S08GT16 Datasheet - Page 149

• Manufacturer Part Number: MC9S08GT16
• Description: Microcontrollers
• Manufacturer: MOTOROLA [Motorola, Inc]

KBEDGn — Keyboard Edge Select for KBI Port Bit n (n = 7–4)
KBF — Keyboard Interrupt Flag
KBACK — Keyboard Interrupt Acknowledge
KBIE — Keyboard Interrupt Enable
KBIMOD — Keyboard Detection Mode
Freescale Semiconductor
Each of these read/write bits selects the polarity of the edges and/or levels that are recognized as trigger
events on the corresponding KBI port pin when it is configured as a keyboard interrupt input
(KBIPEn = 1). Also see the KBIMOD control bit, which determines whether the pin is sensitive to
edges-only or edges and levels.
This read-only status flag is set whenever the selected edge event has been detected on any of the
enabled KBI port pins. This flag is cleared by writing a 1 to the KBACK control bit. The flag will
remain set if KBIMOD = 1 to select edge-and-level operation and any enabled KBI port pin remains
at the asserted level.
KBF can be used as a software pollable flag (KBIE = 0) or it can generate a hardware interrupt request
to the CPU (KBIE = 1).
This write-only bit (reads always return 0) is used to clear the KBF status flag by writing a 1 to
KBACK. When KBIMOD = 1 to select edge-and-level operation and any enabled KBI port pin
remains at the asserted level, KBF is being continuously set so writing 1 to KBACK does not clear the
KBF flag.
This read/write control bit determines whether hardware interrupts are generated when the KBF status
flag equals 1. When KBIE = 0, no hardware interrupts are generated, but KBF can still be used for
software polling.
This read/write control bit selects either edge-only detection or edge-and-level detection. KBI port bits
3 through 0 can detect falling edges-only or falling edges and low levels.
KBI port bits 7 through 4 can be configured to detect either:
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•
1 = Rising edges/high levels.
0 = Falling edges/low levels.
1 = KBI interrupt pending.
0 = No KBI interrupt pending.
1 = KBI hardware interrupt requested when KBF = 1.
0 = KBF does not generate hardware interrupts (use polling).
1 = Edge-and-level detection.
0 = Edge-only detection.
Rising edges-only or rising edges and high levels (KBEDGn = 1)
Falling edges-only or falling edges and low levels (KBEDGn = 0)
MC9S08GB/GT Data Sheet, Rev. 2.3
KBI Registers and Control Bits
149