MC68HC908GR8CD Freescale Semiconductor, MC68HC908GR8CD Datasheet - Page 124

• Manufacturer Part Number: MC68HC908GR8CD
• Description: 8-bit Microcontrollers - MCU 8 Bit 8MHz
• Manufacturer: Freescale Semiconductor

Specifications of MC68HC908GR8CD

• Product Category: 8-bit Microcontrollers - MCU
• Rohs: yes
• Core: HC08
• Data Bus Width: 8 bit
• Maximum Clock Frequency: 8 MHz
• Program Memory Size: 64 KB
• Data Ram Size: 384 B
• Operating Supply Voltage: 3 V to 5 V
• Package / Case: SOIC-28
• Mounting Style: SMD/SMT
• Data Rom Size: 64 KB
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Number Of Programmable I/os: 21
• Program Memory Type: Flash

Keyboard Interrupt (KBI)
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 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
13.7 I/O Registers
These registers control and monitor operation of the keyboard module:
13.7.1 Keyboard Status and Control Register
The keyboard status and control register:
Bits 7–4 — Not used
KEYF — Keyboard Flag Bit
ACKK — Keyboard Acknowledge Bit
IMASKK — Keyboard Interrupt Mask Bit
124
•
•
•
•
•
•
These read-only bits always read as logic 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 logic 0.
Reset clears ACKK.
Writing a 1 to this read/write bit prevents the output of the keyboard interrupt mask from generating
interrupt requests. Reset clears the IMASKK bit.
1 = Keyboard interrupt pending
0 = No keyboard interrupt pending
1 = Keyboard interrupt requests masked
0 = Keyboard interrupt requests not masked
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 13-3. Keyboard Status and Control Register (INTKBSCR)
Bit 7
0
0
MC68HC908GR8 • MC68HC908GR4 Data Sheet, Rev. 7
= Unimplemented
6
0
0
13.7.1 Keyboard Status and Control
5
0
0
4
0
0
KEYF
3
0
ACKK
2
0
0
Register.
IMASKK
1
0
Freescale Semiconductor
MODEK
Bit 0
0