at42qt2100 ATMEL Corporation, at42qt2100 Datasheet - Page 17

• Manufacturer Part Number: at42qt2100
• Description: Qtouch Touch Sensor Ic
• Manufacturer: ATMEL Corporation

9554CX–AT42–11/11
CHANGE Pin in LP Mode: During the sleep portion of LP mode, CHANGE is held low.
If however a change of key state is confirmed, CHANGE goes high and the part runs from then
on in Free Run mode until the host reads the key state and puts the device back into LP mode
or some other mode.
MISO in LP Mode: During the sleep portion of LP mode, MISO floats.
DRDY during LP Mode: DRDY remains high while the QT2100 is sleeping, to indicate to the
host that SPI communications are possible. During an actual acquire burst, DRDY is held low.
Command During LP Mode: The device can be woken from sleep by the SS pin being pulled
low. Note that the SS pin must be pulled high in order for the device to enter its lowest power
sleep mode. If SS is held low, the device enters a higher power sleep mode to enable SPI
communications. The host may perform a normal SPI transfer as shown in
page
After the SPI transfer is completed, the QT2100 will generate a set of three acquire bursts if
LPB = 1, during which DRDY will be low.
The mode and options settings sent from the host to the QT2100 during the SPI transfer take
effect after the set of acquire bursts.
The CHANGE pin will go high at this time if a key is confirmed as touched.
SS Wake pulse: In LP Mode, a wake pulse may be used on the SS pin to either trigger an
LPB acquire burst or to wake the device in advance of communications. The pulse should be
at least 22 µs in duration.
When used prior to communications, there should be a delay of 100 µs to 1 ms between the
end of the SS Pulse and the following SS assertion.
• If either LP mode or Sleep mode is selected, the QT2100 will go back to sleep with DRDY
• If Sync mode is selected, the QT2100 will go back to sleep with DRDY high provided no key
high provided no key is detected as possibly touched.
is detected as possibly touched.
18.
AT42QT2100
Figure 4-2 on
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