PIC16F72X/PIC16LF72X
14.0
CAPACITIVE SENSING
MODULE
sensing module. The capacitive sensing module
requires software and at least one timer resource to
determine the change in frequency. Key features of this
module include:
•
•
•
•
•
Analog MUX for monitoring multiple inputs
Capacitive sensing oscillator
Multiple timer resources
Software control
Operation during Sleep
The capacitive sensing module allows for an interaction
with an end user without a mechanical interface. In a
typical application, the capacitive sensing module is
attached to a pad on a printed circuit board (PCB), which
is electrically isolated from the end user. When the end
user places their finger over the PCB pad, a capacitive
load is added, causing a frequency shift in the capacitive
FIGURE 14-1:
CAPACITIVE SENSING BLOCK DIAGRAM
Timer0 Module
T0CS
T0XCS
F
OSC
/4
T0CKI
0
1
1
0
TMR0
Overflow
Set
T0IF
CPSCH<3:0>
(2)
CPSON
(3)
CPS0
CPS1
CPS2
CPS3
CPS4
CPS5
CPS6
CPS7
CPS8
(1)
CPS9
(1)
CPS10
(1)
Timer1 Module
CPSON
Capacitive
Sensing
Oscillator
CPSOSC
T1CS<1:0>
F
OSC
F
OSC
/4
CPSCLK
CPSOUT
T1OSC/
T1CKI
T1GSEL<1:0>
T1G
Timer1 Gate
Control Logic
EN
TMR1H:TMR1L
CPS11
(1)
CPS12
(1)
CPS13
(1)
CPS14
(1)
CPS15
(1)
CPSRNG<1:0>
Watchdog Timer Module
WDT
Event
TMR2
Overflow
Overflow
Timer2 Module
Postscaler
Set
TMR2IF
LP WDT
OSC
PS<2:0>
WDT
Scaler
Note 1:
Channels CPS<15:8> are implemented on PIC16F724/727/PIC16LF724/727 only.
2:
CPSCH3 is not implemented on PIC16F722/723/726/PIC16LF722/723/726.
3:
If CPSON =
0,
disabling capacitive sensing, no channel is selected.
©
2009 Microchip Technology Inc.
41341E-page 129
MICROCHIP [ MICROCHIP TECHNOLOGY ]
