Datasheet

561
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129K–SAM-D20_datasheet–06/2014
Self-capacitance Sensor Arrangement
The self-capacitance sensor is connected to a single pin on the Peripheral Touch Controller through the Y electrode for
receiving the signal. The sense electrode capacitance is measured by the Peripheral Touch Controller.
Figure 31-4. Self-capacitance Sensor Arrangement
For more information about designing the touch sensor, refer to Buttons, Sliders and Wheels Touch Sensor Design
Guide on http://www.atmel.com.
31.5.2 Clocks
The PTC is clocked by the GCLK_PTC clock. The PTC operates from an asynchronous clock source and the operation is
independent of the main system clock and its derivative clocks, such as the peripheral bus clock (CLK_APB). A number
of clock sources can be selected as the source for the asynchronous GCLK_PTC. The clock source is selected by
configuring the Generic Clock Selection ID in the Generic Clock Control register. For more information about selecting
the clock sources, refer to “GCLK – Generic Clock Controller” on page 79.
The selected clock must be enabled in the Power Manager, before it can be used by the PTC. By default these clocks are
disabled. The frequency range of GCLK_PTC is 400kHz to 4MHz.
For more details, refer to “PM – Power Manager” on page 101.
MCU
PTC
Module
Y
0
Y
1
Y
m
C
y0
C
y1
C
ym
Sensor Capacitance C
y