44.4. Signal Description
Table 44-1. Signal Description for PTC
Name
Type
Description
Y[m:0]
Analog
Y-line (Input/Output)
X[n:0]
Digital
X-line (Output)
Note:
The number of X and Y lines are device dependent. Refer to
Configuration Summary
for details.
Refer to
I/O Multiplexing and Considerations
for details on the pin mapping for this peripheral. One signal
can be mapped on several pins.
Related Links
I/O Multiplexing and Considerations
on page 27
44.5. Product Dependencies
In order to use this Peripheral, configure the other components of the system as described in the
following sections.
44.5.1. I/O Lines
The I/O lines used for analog X-lines and Y-lines must be connected to external capacitive touch sensor
electrodes. External components are not required for normal operation. However, to improve the EMC
performance, a series resistor of 1kΩ or more can be used on X-lines and Y-lines.
44.5.1.1. Mutual-capacitance Sensor Arrangement
A mutual-capacitance sensor is formed between two I/O lines - an X electrode for transmitting and Y
electrode for receiving. The mutual capacitance between the X and Y electrode is measured by the
Peripheral Touch Controller.
Figure 44-3. Mutual Capacitance Sensor Arrangement
PTC
Module
MCU
X
0
X
n
Y
0
Y
m
X
1
Y
1
Sensor Capacitance C
x,y
C
x0,y0
C
x0,y1
C
x0,ym
C
x1,y0
C
x1,y1
C
x1,ym
C
xn,y0
C
xn,y1
C
xn,ym
PTC
Module
Atmel SAM L22G / L22J / L22N [DATASHEET]
Atmel-42402E-SAM L22G / L22J / L22N_Datasheet_Complete-07/2016
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