E6240 Atmel, E6240 Datasheet - Page 20
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E6240
Manufacturer Part Number
E6240
Description
KIT EVAL/DEV USING QT60240-ISG
Manufacturer
Atmel
Series
Quantum, QMatrix™r
Specifications of E6240
Sensor Type
Touch, Capacitive
Sensing Range
16 / 24 Buttons/Keys
Interface
I²C, USB
Voltage - Supply
5V
Embedded
No
Utilized Ic / Part
QT60160, QT60240
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Sensitivity
-
Since noise synchronization is highly effective and
inexpensive to implement, it is strongly advised to take
advantage of it anywhere there is a possibility of
encountering low frequency (i.e. 50/60Hz) electric fields.
Quantum’s QmBtn software can show such noise effects
on signals, and will hence assist in determining the need to
make use of this feature.
If the synchronization feature is enabled but no
synchronization signal exists, the sensor will continue to
operate but with a delay of 100ms before the start of each
matrix scan, and hence will have a slow response time.
SYNC Default value:
SYNC Possible range:
6.12 Sleep Duration - SLEEP
The QT60xx0 is designed to sleep as much as possible to
conserve power. Periodically, the part wakes automatically,
scans the keyboard matrix and then returns to sleep. The
length of time the part sleeps before automatically waking
up can be configured to one of eight different values, via a
look-up table. The look-up table index must be written to
the setups (see Table 6.2, page 22).
Note that when a key changes state, the CHANGE pin can
be made to go active and the device can go into ‘fast
mode’ automatically if the WAKE feature is enabled on that
key (next section).
SLEEP default value:
SLEEP range:
6.13 Wake on Key Touch - WAKE
The device can be configured for full time wake-up from
Sleep mode when specific keys are touched or released
using this feature, in order to improve response time after
each key state change. Once awake the key will remain
awake until the AWAKE function times out (Section 6.14).
Also this feature makes the CHANGE pin go active on a
key touch or key release (Section 3.4).
Each key has its own WAKE configuration bit so that any
combination of keys can be configured for this function.
The time the part will remain awake after any key state
change can also be configured in the Setup block (AWAKE
feature, next section).
Any key, even one where the WAKE feature is not
enabled, will prolong the time the part remains awake once
the part is awake
lQ
0 (Off)
0, 1 (Off, On)
3 (125ms)
0...7 (16ms...2s)
20
In Shift Register mode, the WAKE function is enabled for
all keys, however the CHANGE pin does not function in
this mode. The AWAKE timeout in Shift Register mode is
2.5s (note default setting of AWAKE parameter in Table
6.2).
WAKE Default value:
WAKE Possible range:
6.14 Awake Timeout - AWAKE
After each matrix scan, the part will automatically go to
sleep whenever possible to conserve power, unless there
has been a key state change on a key with the WAKE
feature enabled (Section 6.13), in which case the part will
wake up into ‘fast mode’ which has no sleep states and
operates at the fastest possible speed. The AWAKE
timeout feature determines how long the device will remain
in this mode from the last key state change.
Subsequent key state changes further prolong the AWAKE
interval. In other words, once the part has been awakened
by a change on a WAKE enabled key, the key response
time will be fast for as long as the keyboard remains in
use. Once key activity lapses for a period longer than the
AWAKE timeout, the part will return to sleep mode.
The AWAKE period can be configured to a value between
100ms and 25.5s, in increments of 100ms.
AWAKE default value:
AWAKE range:
AWAKE Timeout accuracy: to within ±50ms
6.15 Drift Hold Time - DHT
Drift Hold Time (DHT) is used to restrict drift on all keys
while one or more keys are activated. DHT defines the
length of time the drift is halted after a key detection.
This feature is particularly useful in cases of high-density
keypads where touching a key or hovering a finger over the
keypad would cause untouched keys to drift, and therefore
create a sensitivity shift, and ultimately inhibit any touch
detection.
DHT can be configured to a value of between 100ms and
25.5s, in increments of 100ms. Setting this parameter to 0
will disable this feature and the drift compensation on any
key will not be dependent on the state of other keys.
DHT default value:
DHT range:
10 (1s)
0...255 (Off, 100ms...25.5s)
1 (On)
0, 1 (Off, On)
QT60240-ISG R8.06/0906
25 (2.5s)
1...255 (100ms...25.5s)