QST608 ST Microelectronics, QST608 Datasheet - Page 15

• Manufacturer Part Number: QST608
• Description: Capacitive touch sensor device
• Manufacturer: ST Microelectronics

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QST608
4.5
4.6
4.7
General-purpose outputs
Up to 5 general-purpose outputs can be controlled using the I
purpose pins are configured in output push pull mode 0 by default. Their state can be
changed using the SET_GPIO_STATE I
Figure 4.
IRQ pin
The IRQ pin is an open drain output with an internal pull-up. It can be used to inform the
Master device about any change in the key status. The IRQ line is pulled low every time the
state of any of the enabled keys changes. This includes any change in the touch state of the
key, position change of the rotor/slider, a faulty key or new calibration of one or more keys.
The reported changes may then be accessed by the Master device by using the
GET_KEY_STATE command.
To improve communication response time, this signal suspends Low Power mode until the
Master device has issued a communication with the QST device.
Communication packet
The communication between the Master device and the QST608 (Slave) consists of two
standard I
The first frame is sent by the Master device using the QST608 device address with the write
bit set. The data bytes consist of the command byte which is eventually followed by the
parameters and a checksum byte.
The second one is sent by the Master device using the QST608 device address with the
write bit reset. The QST608 completes the frame with data according to the command
previously sent by the Master device. The device finishes the frame by sending a checksum
byte for communication integrity verification.
If the read frame is omitted, the command may not be taken into account and the low power
mode (if active) is suspended.
To initiate the communicate with the QST608, the Master device must send the
GET_DEVICE_INFO command in order to unlock access to all the other commands.
2
C frames.
Optional LED schematic
GPO
n
2
C command.
V
UNREG
2
C interface. These general-
R
Device operating mode
C (10 nF)
Ai12570
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