AT91SAM9G45-EKES Atmel, AT91SAM9G45-EKES Datasheet - Page 942

• Manufacturer Part Number: AT91SAM9G45-EKES
• Description: KIT EVAL FOR AT91SAM9G45
• Manufacturer: Atmel
• Series: AT91SAM Smart ARMr
• Type: MCUr

Specifications of AT91SAM9G45-EKES

• Contents: Board
• Processor To Be Evaluated: SAM9G45
• Data Bus Width: 32 bit
• Interface Type: I2C, SPI, UART
• Maximum Operating Temperature: + 50 C
• Minimum Operating Temperature: - 10 C
• Operating Supply Voltage: 1.8 V to 3.3 V
• For Use With/related Products: AT91SAM9G45
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: Q4626953

40.7.4
942
AT91SAM9G45
Pen Detect Method
When there is no contact, it is not necessary to perform conversion. However, it is important to
detect a contact by keeping the power consumption as low as possible.
The proposed implementation polarizes the vertical panel by closing the switch on X
the horizontal panel by an embedded resistor connected to Y
switch. Since there is no contact, no current is flowing and there is no related power consump-
tion. As soon as a contact occurs, a current is flowing in the touch screen and a schmitt trigger
detects the voltage in the resistor.
The Touch Screen Interrupt configuration is entered by programming the bit PENDET in the
“TSADCC Mode
tor are both closed, except when a touch screen conversion is in progress.
To complete the circuit, a programmable debouncer is placed at the output of the schmitt trigger.
This debouncer is programmable at 1 ADC Clock period, useful when the system is running at
Slow Clock, or at up to 2
Screen panel when the system is running at high speed. The debouncer length can be selected
by programming the field PENDBC in
Resistor
Resistor
Switch
Switch
X
X
VDDANA
M
P
GND
XPos Measure(Yp)
Rp
Register”. If this bit is written at 1, the switch on X
Open
circuit
Y
Y
P
15
M
ADC Clock periods, but better used to filter noise on the Touch
Resistor
Switch
“TSADCC Mode
X
X
M
P
GND
Z1 Measure(Xp)
Resistor
Switch
Rp
VDDANA
Open
circuit
Register”.
Y
Y
P
M
M
. This resistor is enabled by a fifth
X
X
M
P
P
Open
GND
and the switch on the resis-
circuit
Z2 Measure(Xp)
Resistor
Switch
Rp
6438F–ATARM–21-Jun-10
VDDANA
Y
Y
Resistor
P
M
Switch
P
and ties