68HC908RF Datasheet, PDF (95/188 Pages) Motorola, Inc – Microcontrollers

Freescale Semiconductor, Inc.
Keyboard/External Interrupt Module (KBI)
Functional Description
ACKI
RESET
VECTOR
FETCH
DECODER
V_DD
INTERNAL
PULLUP
DEVICE
IRQ
V_DD
D ^CLR Q
CK
IRQ1
LATCH
SYNCHRO-
NIZER
IMASKI
MODEI
HIGH
VOLTAGE
DETECT
Figure 7-2. IRQ Block Diagram
TO CPU FOR
BIL/BIH
INSTRUCTIONS
IRQ1F
IRQ1
INTERRUPT
REQUEST
KEYBOARD
INTERRUPT
REQUEST
IRQ1/KEYBOARD
INTERRUPT
REQUEST
TO MODE
SELECT
LOGIC
Addr.
$001A
$001B
Register Name
Bit 7
6
5
4
3
2
IRQ and Keyboard Status Read:
and Control Register _Write:
(INTKBSCR)
See page 101. ^Reset:
Keyboard Interrupt Enable ^Read:
Register (INTKBIER) Write:
See page 102. _Reset:
IRQ1F
R
0
0
0
0
IMASKI
ACKI
0
0
KBIE6 KBIE5
0
0
= Unimplemented
MODEI
0
KEYF
R
0
0
ACKK
0
KBIE4 KBIE3 KBIE2
0
0
0
R = Reserved
Figure 7-3. IRQ and Keyboard I/O Register Summary
1
Bit 0
IMASKK MODEK
0
0
0
KBIE1
0
0
Interrupt signals on the IRQ pin are latched into the IRQ1 latch. Keyboard interrupts
are latched in the keyboard interrupt latch. An interrupt latch remains set until one
of these actions occurs:
• Vector fetch — A vector fetch automatically generates an interrupt
acknowledge signal that clears IRQ1 latch and keyboard interrupt latch.
• Software clear — Software can clear an interrupt latch by writing to the
appropriate acknowledge bit in the interrupt status and control register
(INTKBSCR). Writing a 1 to the ACKI bit clears the IRQ1 latch. Writing a 1
to the ACKK bit clears the keyboard interrupt latch.
• Reset — A reset automatically clears both interrupt latches.
MC68HC908RF2 — Rev. 4.0
MOTOROLA
Keyboard/External Interrupt Module (KBI)
For More Information On This Product,
Go to: www.freescale.com
Data Sheet
95