MC68HC08JB1 Datasheet, PDF (193/216 Pages) Motorola, Inc – Microcontrollers

13.8 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 (BFCR) 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 logic 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 logic 0 to the BCFE
bit. With BCFE at logic 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 13.9.1 Keyboard Status and
Control Register.)
13.9 I/O Registers
These registers control and monitor operation of the keyboard module:
• Keyboard status and control register (KBSCR)
• Keyboard interrupt enable register (KBIER)
13.9.1 Keyboard Status and Control Register
The keyboard status and control register:
• Flags keyboard interrupt requests
• Acknowledges keyboard interrupt requests
• Masks keyboard interrupt requests
• Controls keyboard interrupt triggering sensitivity
MC68HC08JB1 — Rev. 2.1
Freescale Semiconductor
Technical Data
193