mc68hc908gr8b Freescale Semiconductor, Inc, mc68hc908gr8b Datasheet - Page 101

• Manufacturer Part Number: mc68hc908gr8b
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

9.5.2 Stop Mode
The keyboard module remains active in stop mode. Clearing the IMASKK bit in the keyboard status and
control register enables keyboard interrupt requests to bring the MCU out of stop mode.
9.6 Keyboard Module During Break Interrupts
The system integration module (SIM) controls whether the keyboard interrupt latch can be cleared during
the break state. The BCFE bit in the break flag control register (SBFCR) enables software to clear status
bits during the break state.
To allow software to clear the keyboard interrupt latch during a break interrupt, write a 1 to the BCFE bit.
If a latch is cleared during the break state, it remains cleared when the MCU exits the break state.
To protect the latch during the break state, write a 0 to the BCFE bit. With BCFE at 0 (its default state),
writing to the keyboard acknowledge bit (ACKK) in the keyboard status and control register during the
break state has no effect. See
9.7 I/O Registers
These registers control and monitor operation of the keyboard module:
9.7.1 Keyboard Status and Control Register
The keyboard status and control register:
Bits 7–4 — Not used
KEYF — Keyboard Flag Bit
ACKK — Keyboard Acknowledge Bit
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These read-only bits always read as 0s.
This read-only bit is set when a keyboard interrupt is pending. Reset clears the KEYF bit.
Writing a 1 to this write-only bit clears the keyboard interrupt request. ACKK always reads as 0. Reset
clears ACKK.
1 = Keyboard interrupt pending
0 = No keyboard interrupt pending
Keyboard status and control register (INTKBSCR)
Keyboard interrupt enable register (INTKBIER)
Flags keyboard interrupt requests
Acknowledges keyboard interrupt requests
Masks keyboard interrupt requests
Controls keyboard interrupt triggering sensitivity
Address: $001A
Reset:
Read:
Write:
Figure 9-4. Keyboard Status and Control Register (INTKBSCR)
Bit 7
0
0
9.7.1 Keyboard Status and Control
= Unimplemented
6
0
0
MC68HC908GR8B Data Sheet, Rev. 3.0
5
0
0
4
0
0
KEYF
3
0
Register.
Keyboard Module During Break Interrupts
ACKK
2
0
0
IMASKK
1
0
MODEK
Bit 0
0
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