Atmel ARM-Based Evaluation Kit AT91SAM9N12-EK AT91SAM9N12-EK Data Sheet
Product codes
AT91SAM9N12-EK
870
SAM9N12/SAM9CN11/SAM9CN12 [DATASHEET]
11063K–ATARM–05-Nov-13
42.7
Touchscreen
42.7.1 Touchscreen
Mode
The TSMODE parameter of
is used to enable/disable the Touchscreen functionality,
to select the type of screen (4-wire or 5-wire) and, in the case of a 4-wire screen, to activate (or not) the pressure
measurement.
measurement.
In 4-wire mode, channel 0, 1, 2 and 3 must not be used for classic ADC conversions. Likewise, in 5-wire mode, channel
0, 1, 2, 3, and 4 must not be used for classic ADC conversions.
0, 1, 2, 3, and 4 must not be used for classic ADC conversions.
42.7.2 4-wire Resistive Touchscreen Principles
A resistive touchscreen is based on two resistive films, each one being fitted with a pair of electrodes, placed at the top
and bottom on one film, and on the right and left on the other. In between, there is a layer acting as an insulator, but also
enables contact when you press the screen. This is illustrated in
and bottom on one film, and on the right and left on the other. In between, there is a layer acting as an insulator, but also
enables contact when you press the screen. This is illustrated in
.
The TSADC controller has the ability to perform without external components:
Position Measurement
Pressure Measurement
Pen Detection
Figure 42-6. Touchscreen Position Measurement
X
M
X
P
Y
M
Y
P
X
P
X
M
Y
P
VDD
GND
Volt
Horizontal Position Detection
Y
P
Y
M
X
P
VDD
GND
Volt
Vertical Position Detection
Pen
Contact