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* Analog Devices AD7879(-1)/AD7889(-1) touchscreen interface (SPI/I2C)
Required properties:
- compatible : for SPI slave, use "adi,ad7879"
for I2C slave, use "adi,ad7879-1"
- reg : SPI chipselect/I2C slave address
See spi-bus.txt for more SPI slave properties
- interrupts : touch controller interrupt
- touchscreen-max-pressure : maximum reported pressure
- adi,resistance-plate-x : total resistance of X-plate (for pressure
calculation)
Optional properties:
- touchscreen-swapped-x-y : X and Y axis are swapped (boolean)
- adi,first-conversion-delay : 0-12: In 128us steps (starting with 128us)
13 : 2.560ms
14 : 3.584ms
15 : 4.096ms
This property has to be a '/bits/ 8' value
- adi,acquisition-time : 0: 2us
1: 4us
2: 8us
3: 16us
This property has to be a '/bits/ 8' value
- adi,median-filter-size : 0: disabled
1: 4 measurements
2: 8 measurements
3: 16 measurements
This property has to be a '/bits/ 8' value
- adi,averaging : 0: 2 middle values (1 if median disabled)
1: 4 middle values
2: 8 middle values
3: 16 values
This property has to be a '/bits/ 8' value
- adi,conversion-interval: : 0 : convert one time only
1-255: 515us + val * 35us (up to 9.440ms)
This property has to be a '/bits/ 8' value
- gpio-controller : Switch AUX/VBAT/GPIO pin to GPIO mode
Example:
touchscreen0@2c {
compatible = "adi,ad7879-1";
reg = <0x2c>;
interrupt-parent = <&gpio1>;
interrupts = <13 IRQ_TYPE_EDGE_FALLING>;
touchscreen-max-pressure = <4096>;
adi,resistance-plate-x = <120>;
adi,first-conversion-delay = /bits/ 8 <3>;
adi,acquisition-time = /bits/ 8 <1>;
adi,median-filter-size = /bits/ 8 <2>;
adi,averaging = /bits/ 8 <1>;
adi,conversion-interval = /bits/ 8 <255>;
};
touchscreen1@1 {
compatible = "adi,ad7879";
spi-max-frequency = <5000000>;
reg = <1>;
spi-cpol;
spi-cpha;
gpio-controller;
interrupt-parent = <&gpio1>;
interrupts = <13 IRQ_TYPE_EDGE_FALLING>;
touchscreen-max-pressure = <4096>;
adi,resistance-plate-x = <120>;
adi,first-conversion-delay = /bits/ 8 <3>;
adi,acquisition-time = /bits/ 8 <1>;
adi,median-filter-size = /bits/ 8 <2>;
adi,averaging = /bits/ 8 <1>;
adi,conversion-interval = /bits/ 8 <255>;
};
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