FXTH870xD
Sensors
Freescale Semiconductor, Inc.
49
7
Keyboard Interrupt
The FXTH870xD has a KBI module with general purpose I/O pins.
7.1
Features
The KBI features include:
•
Up to four keyboard interrupt pins with individual pin enable bits.
•
Each keyboard interrupt pin is programmable as falling edge (or rising edge) only, or both falling edge and low level (or both
rising edge and high level) interrupt sensitivity.
•
One software enabled keyboard interrupt.
•
Exit from low-power modes.
7.2
Modes of Operation
This section defines the KBI operation in WAIT, STOP, and BACKGROUND DEBUG modes.
7.2.1
KBI in STOP Modes
The KBI operates asynchronously in STOP4 mode if enabled before executing the STOP instruction. Therefore, an enabled KBI
pin (KBPE[3:0]) can be used to bring the MCU out of STOP4 mode if the KBI interrupt is enabled (KBIE = 1).
During STOP1 mode, the KBI is disabled. In some systems, the pins associated with the KBI may be sources of wakeup from
STOP1, see the STOP modes section in the
. Upon wakeup from STOP1 mode, the KBI module will be in the reset
state.
7.2.2
KBI in ACTIVE BACKGROUND mode
When the microcontroller is in ACTIVE BACKGROUND mode, the KBI will continue to operate normally.
7.3
Block Diagram
The block diagram for the keyboard interrupt module is shown
.
Figure 36. KBI Block Diagram
7.4
External Signal Description
The KBI input pins can be used to detect either falling edges, or both falling edge and low level interrupt requests. The KBI input
pins can also be used to detect either rising edges, or both rising edge and high level interrupt requests.
The signal properties of KBI are shown in
.
Table 39. Signal Properties
Signal
Function
I/O
KBIPn
Keyboard interrupt pins
I
D
Q
CK
CLR
V
DD
KBMOD
KBIE
KEYBOARD
INTERRUPT FF
KBACK
RESET
SYNCHRONIZER
KBF
STOP BYPASS
STOP
BUSCLK
KBIPEn
0
1
S
KBEDGn
KBIPE0
0
1
S
KBEDG0
KBIP0
KBIPn
KBI
INTERRUP
Содержание FXTH870 D Series
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