Microchip AT42QT1050 Five-channel Touch Sensor IC
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The AT42QT1050 (QT1050) is a QTouchADC sensor device. The device can sense from
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one to five keys, dependent on mode. The QT1050 includes all signal processing
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functions necessary to provide stable sensing under a wide variety of changing
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conditions, and the outputs are fully debounced.
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The touchkey device node should be placed inside an I2C bus node.
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Required properties:
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- compatible: Must be "microchip,qt1050"
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- reg: The I2C address of the device
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- interrupts: The sink for the touchpad's IRQ output,
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see ../interrupt-controller/interrupts.txt
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Optional properties:
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- wakeup-source: touch keys can be used as a wakeup source
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Each button (key) is represented as a sub-node:
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Each not specified key or key with linux,code set to KEY_RESERVED gets disabled
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in HW.
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Subnode properties:
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- linux,code: Keycode to emit.
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- reg: The key number. Valid values: 0, 1, 2, 3, 4.
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Optional subnode-properties:
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If a optional property is missing or has a invalid value the default value is
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taken.
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- microchip,pre-charge-time-ns:
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Each touchpad need some time to precharge. The value depends on the mechanical
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layout.
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Valid value range: 0 - 637500; values must be a multiple of 2500;
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default is 0.
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- microchip,average-samples:
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Number of data samples which are averaged for each read.
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Valid values: 1, 4, 16, 64, 256, 1024, 4096, 16384; default is 1.
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- microchip,average-scaling:
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The scaling factor which is used to scale the average-samples.
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Valid values: 1, 2, 4, 8, 16, 32, 64, 128; default is 1.
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- microchip,threshold:
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Number of counts to register a touch detection.
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Valid value range: 0 - 255; default is 20.
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Example:
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QT1050 with 3 non continuous keys, key2 and key4 are disabled.
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touchkeys@41 {
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compatible = "microchip,qt1050";
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reg = <0x41>;
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interrupt-parent = <&gpio0>;
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interrupts = <17 IRQ_TYPE_EDGE_FALLING>;
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up@0 {
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reg = <0>;
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linux,code = <KEY_UP>;
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microchip,average-samples = <64>;
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microchip,average-scaling = <16>;
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microchip,pre-charge-time-ns = <10000>;
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};
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right@1 {
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reg = <1>;
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linux,code = <KEY_RIGHT>;
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microchip,average-samples = <64>;
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microchip,average-scaling = <8>;
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};
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down@3 {
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reg = <3>;
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linux,code = <KEY_DOWN>;
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microchip,average-samples = <256>;
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microchip,average-scaling = <16>;
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};
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};
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