IQS550EV03 S Azoteq, IQS550EV03 S Datasheet - Page 12

• Manufacturer Part Number: IQS550EV03 S
• Description: Touch Sensor Development Tools Trackpad Demo for IQS550
• Manufacturer: Azoteq

Specifications of IQS550EV03 S

• Tool Is For Evaluation Of: IQS550
• Interface Type: I2C, SPI
• Operating Voltage: 1.65 V to 3.6 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C

If the count value increases with more than
this threshold value, then a touch condition is
true.
A touch is NOT calculated for the ProxMode
channel, but two sets of thresholds are
available for the trackpad and non-trackpad
channels
3.13 Snap Sensitivity
The Snap threshold is a delta value BELOW
the Long-Term Average of the channel. When
a snap is performed, a self capacitive effect is
observed, and the sample value will decrease.
To be able to distinguish between a snap, and
a normal touch release, the hardware must be
designed so that a snap forces the samples
below the Long-Term Average value. A 16-bit
value can be selected for this delta.
When a user touches the key, the samples on
that specific channel will increase and a
normal touch and prox output will trigger.
When the user pushes the button down
(snap), the samples will decrease (removing
the prox and touch outputs) below the Long-
Term Average value, and a snap output can
be observed.
One global Snap threshold is implemented.
3.14 Output Debounce
All the channel outputs (proximity, touch and
snap) are debounced
selectable debounce values.
debounce values are shown in the table, note
that a debounce value = 1 means that two
samples satisfying the condition must be met
before the output is activated.
value of 0 thus means no debouncing takes
place. The default touch debounce setting is
set to no debouncing. This is due to the fact
that with a 15x10 sensor, debouncing adds
too much delay, and fast movements on the
touchpanel cannot be debounced fast enough
to provide reliable XY output data.
advanced sensitivity of the sensors, a touch is
regarded as a large deviation this does not
pose any problems.
Copyright © Azoteq (Pty) Ltd
All Rights Reserved.
according
A debounce
The
ProxSense
With the
to the
IQ Switch
default
IQS550 Trackpad Datasheet
®
3.15 Touch and Proximity XY Data
Five XY co-ordinates are available to the
master.
touches/proximity points sensed on the sensor
panel. The XY data is sent out in order, from
hardest to least hard touch/prox.
however tracks each specific XY position from
cycle to cycle (since they will move in position
relative to their touch strength) and attaches
the relating ID tag with each co-ordinate.
5 unique ID tags are available for TOUCH co-
ordinates, namely values of 1-5, and 5 ID‟s for
HOVER co-ordinates, namely 129 - 133.
256 steps are implemented between the
relative Rx‟s and also between the relative
Tx‟s, giving x coordinates that range from 0 to
(256 x (TrackpadRxs-1)).
The Y coordinates will have an output range
from 0 to (256 x (TrackpadTxs-1)). Thus in a
15x10 system: (0 < y < 3584) and (0 < x <
2304).
It is not necessary to read the proximity, touch
or snap status data to obtain a global picture
of the touch panel status. The XY data stream
contains all information required during normal
operation.
The XY data stream is lead by an information
byte showing certain status bits, as well as
how many active co-ordinates are currently
available (the number of touches + hovers).
For each co-ordinate, the ID tag is sent first,
followed by an X co-ordinate, a Y co-ordinate,
and finally the touch strength. All of these are
2 bytes each.
A total of 5 co-ordinates are always available
to be read, but if the information byte indicates
fewer co-ordinates are active, the master is
allowed to stop reading after the relative co-
ordinate. A global snap indication bit is also
Revision 1.04
Series
®
Proximity
Touch
Snap
Table 3.1
These are the 5 „hardest/biggest‟
Set
4
0
1
Debounce values
Clear
November 2012
4
0
1
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