s908ey16g2vfar Freescale Semiconductor, Inc, s908ey16g2vfar Datasheet - Page 117

• Manufacturer Part Number: s908ey16g2vfar
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

To allow software to clear status bits during a break interrupt, write a 1 to BCFE. If a status bit is cleared
during the break state, it remains cleared when the MCU exits the break state.
To protect status bits during the break state, write a 0 to BCFE. With BCFE cleared (its default state),
software can read and write registers during the break state without affecting status bits. Some status bits
have a two-step read/write clearing procedure. If software does the first step on such a bit before the
break, the bit cannot change during the break state as long as BCFE is cleared. After the break, doing the
second step clears the status bit.
10.7 I/O Signals
The KBI module can share its pins with the general-purpose I/O pins. See
that are shared.
10.7.1 KBI Input Pins (KBI7:KBI0)
Each KBI pin is independently programmable as an external interrupt source. KBI pin polarity can be
controlled independently. Each KBI pin when enabled will automatically configure the appropriate
pullup/pulldown device based on polarity.
10.8 Registers
The following registers control and monitor operation of the KBI module:
10.8.1 Keyboard Status and Control Register (KBSCR)
Features of the KBSCR:
Bits 7–4 — Not used
KEYF — Keyboard Flag Bit
Freescale Semiconductor
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This read-only bit is set when a keyboard interrupt is pending.
1 = Keyboard interrupt pending
0 = No keyboard interrupt pending
KBSCR (keyboard interrupt status and control register)
KBIER (keyboard interrupt enable register)
KBIPR (keyboard interrupt polarity register)
Flags keyboard interrupt requests
Acknowledges keyboard interrupt requests
Masks keyboard interrupt requests
Controls keyboard interrupt triggering sensitivity
Address: $001A
Reset:
Read:
Write:
Figure 10-3. Keyboard Status and Control Register (KBSCR)
Bit 7
0
0
MC68HC908EY16A • MC68HC908EY8A Data Sheet, Rev. 1
= Unimplemented
6
0
0
5
0
0
4
0
0
KEYF
3
0
ACKK
2
0
0
Figure 10-1
IMASKK
1
0
MODEK
Bit 0
for the port pins
0
I/O Signals
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