0001 Microchip AT42QT1050 Five-channel Touch Sensor IC
0002
0003 The AT42QT1050 (QT1050) is a QTouchADC sensor device. The device can sense from
0004 one to five keys, dependent on mode. The QT1050 includes all signal processing
0005 functions necessary to provide stable sensing under a wide variety of changing
0006 conditions, and the outputs are fully debounced.
0007
0008 The touchkey device node should be placed inside an I2C bus node.
0009
0010 Required properties:
0011 - compatible: Must be "microchip,qt1050"
0012 - reg: The I2C address of the device
0013 - interrupts: The sink for the touchpad's IRQ output,
0014 see ../interrupt-controller/interrupts.txt
0015
0016 Optional properties:
0017 - wakeup-source: touch keys can be used as a wakeup source
0018
0019 Each button (key) is represented as a sub-node:
0020
0021 Each not specified key or key with linux,code set to KEY_RESERVED gets disabled
0022 in HW.
0023
0024 Subnode properties:
0025 - linux,code: Keycode to emit.
0026 - reg: The key number. Valid values: 0, 1, 2, 3, 4.
0027
0028 Optional subnode-properties:
0029
0030 If a optional property is missing or has a invalid value the default value is
0031 taken.
0032
0033 - microchip,pre-charge-time-ns:
0034 Each touchpad need some time to precharge. The value depends on the mechanical
0035 layout.
0036 Valid value range: 0 - 637500; values must be a multiple of 2500;
0037 default is 0.
0038 - microchip,average-samples:
0039 Number of data samples which are averaged for each read.
0040 Valid values: 1, 4, 16, 64, 256, 1024, 4096, 16384; default is 1.
0041 - microchip,average-scaling:
0042 The scaling factor which is used to scale the average-samples.
0043 Valid values: 1, 2, 4, 8, 16, 32, 64, 128; default is 1.
0044 - microchip,threshold:
0045 Number of counts to register a touch detection.
0046 Valid value range: 0 - 255; default is 20.
0047
0048 Example:
0049 QT1050 with 3 non continuous keys, key2 and key4 are disabled.
0050
0051 touchkeys@41 {
0052 compatible = "microchip,qt1050";
0053 reg = <0x41>;
0054 interrupt-parent = <&gpio0>;
0055 interrupts = <17 IRQ_TYPE_EDGE_FALLING>;
0056
0057 up@0 {
0058 reg = <0>;
0059 linux,code = <KEY_UP>;
0060 microchip,average-samples = <64>;
0061 microchip,average-scaling = <16>;
0062 microchip,pre-charge-time-ns = <10000>;
0063 };
0064
0065 right@1 {
0066 reg = <1>;
0067 linux,code = <KEY_RIGHT>;
0068 microchip,average-samples = <64>;
0069 microchip,average-scaling = <8>;
0070 };
0071
0072 down@3 {
0073 reg = <3>;
0074 linux,code = <KEY_DOWN>;
0075 microchip,average-samples = <256>;
0076 microchip,average-scaling = <16>;
0077 };
0078 };
