AT32UC3L064-D3HES ATMEL [ATMEL Corporation], AT32UC3L064-D3HES Datasheet - Page 608

• Manufacturer Part Number: AT32UC3L064-D3HES
• Manufacturer: ATMEL [ATMEL Corporation]

26.7.5
32099D–06/2010
Pen Detect
If no contact is applied to the touch screen films, any touch screen conversion result will be
undefined as the film being measured is floating. This can be avoided by enabling Pen Detect
and only trigger touch screen conversions when the Pen Contact (PENCNT) status bit in the
Status Register (SR) is one. Pen Detect is enabled by writing a one to the Pen Detect (PENDET)
bit in the Mode Register (MR).
When Pen Detect is enabled, the ADCIFB grounds the vertical panel by applying GND to X
X
will in this mode be tristated. Since there is no contact, no current is flowing and there is no
related power consumption. As soon as a contact occurs, GND will propagate to Y
down Y
A programmable debouncing filter can be used to filter out false pen detects because of noise.
The debouncing filter is programmable from one CLK_ADC period and up to 2
ods. The debouncer length is set by writing to the PENDBC field in MR.
Figure 26-4. Touch Screen Pen Detect
The Touch Screen Pen Detect can be used to generate an ADCIFB interrupt request or it can be
used to trig a conversion, so that a position can be measured as soon as a contact is detected.
The Pen Detect Mode generates two types of status signals, reported in the Status Register
(SR):
Before a current change is reflected in the SR, the new status must be stable for the duration of
the debouncing time.
Both status conditions can generate an interrupt request if the corresponding bit in the Interrupt
Mask Register (IMR) is one. Refer to
M
• The bit PENCNT is set when current flows and remains set until current stops.
• The bit NOCNT is set when no current flows and remains set until current flows.
and polarizes the horizontal panel by enabling pull-up on the pin connected to Y
X
Y
X
Y
M
M
P
P
P
, allowing the contact to be registered by the ADCIFB.
GND
Tristate
GND
Pullup
Touch Screen
Sequencer
Section 26.6.11 on page
To the ADC
AT32UC3L016/32/64
602.
Debouncer
PENDBC
Pen Interrupt
15
CLK_ADC peri-
P
. The Y
M
by pulling
P
M
and
608
pin