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Documentation / devicetree / bindings / input / ads7846.txt




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Based on kernel version 4.8. Page generated on 2016-10-06 23:12 EST.

1	Device tree bindings for TI's ADS7843, ADS7845, ADS7846, ADS7873, TSC2046
2	SPI driven touch screen controllers.
3	
4	The node for this driver must be a child node of a SPI controller, hence
5	all mandatory properties described in
6	
7		Documentation/devicetree/bindings/spi/spi-bus.txt
8	
9	must be specified.
10	
11	Additional required properties:
12	
13		compatible		Must be one of the following, depending on the
14					model:
15						"ti,tsc2046"
16						"ti,ads7843"
17						"ti,ads7845"
18						"ti,ads7846"
19						"ti,ads7873"
20	
21		interrupt-parent
22		interrupts		An interrupt node describing the IRQ line the chip's
23					!PENIRQ pin is connected to.
24		vcc-supply		A regulator node for the supply voltage.
25	
26	
27	Optional properties:
28	
29		ti,vref-delay-usecs		vref supply delay in usecs, 0 for
30						external vref (u16).
31		ti,vref-mv			The VREF voltage, in millivolts (u16).
32						Set to 0 to use internal references
33						(ADS7846).
34		ti,keep-vref-on			set to keep vref on for differential
35						measurements as well
36		ti,swap-xy			swap x and y axis
37		ti,settle-delay-usec		Settling time of the analog signals;
38						a function of Vcc and the capacitance
39						on the X/Y drivers.  If set to non-zero,
40						two samples are taken with settle_delay
41						us apart, and the second one is used.
42						~150 uSec with 0.01uF caps (u16).
43		ti,penirq-recheck-delay-usecs	If set to non-zero, after samples are
44						taken this delay is applied and penirq
45						is rechecked, to help avoid false
46						events.  This value is affected by the
47						material used to build the touch layer
48						(u16).
49		ti,x-plate-ohms			Resistance of the X-plate,
50						in Ohms (u16).
51		ti,y-plate-ohms			Resistance of the Y-plate,
52						in Ohms (u16).
53		ti,x-min			Minimum value on the X axis (u16).
54		ti,y-min			Minimum value on the Y axis (u16).
55		ti,x-max			Maximum value on the X axis (u16).
56		ti,y-max			Minimum value on the Y axis (u16).
57		ti,pressure-min			Minimum reported pressure value
58						(threshold) - u16.
59		ti,pressure-max			Maximum reported pressure value (u16).
60		ti,debounce-max			Max number of additional readings per
61						sample (u16).
62		ti,debounce-tol			Tolerance used for filtering (u16).
63		ti,debounce-rep			Additional consecutive good readings
64						required after the first two (u16).
65		ti,pendown-gpio-debounce	Platform specific debounce time for the
66						pendown-gpio (u32).
67		pendown-gpio			GPIO handle describing the pin the !PENIRQ
68						line is connected to.
69		wakeup-source			use any event on touchscreen as wakeup event.
70						(Legacy property support: "linux,wakeup")
71	
72	
73	Example for a TSC2046 chip connected to an McSPI controller of an OMAP SoC::
74	
75		spi_controller {
76			tsc2046@0 {
77				reg = <0>;	/* CS0 */
78				compatible = "ti,tsc2046";
79				interrupt-parent = <&gpio1>;
80				interrupts = <8 0>;	/* BOOT6 / GPIO 8 */
81				spi-max-frequency = <1000000>;
82				pendown-gpio = <&gpio1 8 0>;
83				vcc-supply = <&reg_vcc3>;
84	
85				ti,x-min = /bits/ 16 <0>;
86				ti,x-max = /bits/ 16 <8000>;
87				ti,y-min = /bits/ 16 <0>;
88				ti,y-max = /bits/ 16 <4800>;
89				ti,x-plate-ohms = /bits/ 16 <40>;
90				ti,pressure-max = /bits/ 16 <255>;
91	
92				wakeup-source;
93			};
94		};
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