IQS211_16 Datasheet, PDF (9/29 Pages) List of Unclassifed Manufacturers – Pin compatible with IQS127/128/227/228

ProxSense^® Series
3.1.7 Automatic Calibration
Proven Automatic Tuning Implementation
(ATI) algorithms are used to calibrate the
device to the sense electrode. This
algorithm is optimised for applications
where a fixed detection distance (in mid-air)
is required for failure safe detection.
3.1.8 Capacitive sensing method
The charge transfer method of capacitive
sensing is employed on the IQS211. (The
charge transfer principle is thoroughly
described in the application note: “AZD004
- Azoteq Capacitive Sensing”.)
3.2 Operation
3.2.1 Device Setup
The device may be purchased pre-
configured (large orders or popular
configurations), programmed in-circuit
during production or simply setup via I²C.
3.2.2 Movement filter response
The movement filter runs continually and
the dedicated digital output will activate in
PFM (pulse frequency modulation), PWM
or latched mode.
3.2.3 External control
With certain user interfaces, the
“multifunction IO2” (optional line to connect
to master device) can be used to signal:
 a “halt (sleep mode) and reseed” or
“reduce sensitivity” in MOV&INPUT
mode.
 a “halt (sleep mode) and reseed” in
ACT&MOV mode. When enabled, the
ACT output reads the input periodically.
RESEED
A short pulse (t > 15ms, t < 25ms) will
force the reference counts (long-term
average) to match the actual counts
(capacitance of sensor). The short pulse
for a reseed operation also applies to the
user configurable input option: “Reduce
sensitivity”.
HALT CHARGE (& RESET)
By writing the pin low for a longer time (t >
50ms), will force the IC into “halt charge”
for low current consumption. It is important
to consider current through the pull-up
resistor when in sleep mode.
The IC will perform a soft reset as soon as
the pin is released after 50ms or more.
With a soft reset the IC will remember the
activation state when going into the “halt
charge” mode. The state will be recalled at
the reset operation and cleared along with
the calibration.
In order to achieve a “halt charge” state
with minimal power consumption it is
recommended to configure the MCU
output as push-pull for the input pin and
perform the “halt charge”. With the
“movement latch” function defined, do the
operation twice to clear a possible
activation at the time of calling a “halt
charge”.
REDUCE SENSITIVITY
With a configurable bit the system
sensitivity may be changed. The input may
be used to reduce sensitivity in the
following way:
 AC filter doubles in strength
 Proximity threshold (filter halt) is
increased by 4 counts
 Activation threshold is increased by
10 counts
 Movement sensitivity threshold is
not changed
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IQS211 Datasheet v1.4
Check for latest datasheet
Page 9 of 29
October 2016