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Documentation / devicetree / bindings / input / ads7846.txt




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Based on kernel version 3.16. Page generated on 2014-08-06 21:37 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		ti,keep-vref-on			set to keep vref on for differential
33						measurements as well
34		ti,swap-xy			swap x and y axis
35		ti,settle-delay-usec		Settling time of the analog signals;
36						a function of Vcc and the capacitance
37						on the X/Y drivers.  If set to non-zero,
38						two samples are taken with settle_delay
39						us apart, and the second one is used.
40						~150 uSec with 0.01uF caps (u16).
41		ti,penirq-recheck-delay-usecs	If set to non-zero, after samples are
42						taken this delay is applied and penirq
43						is rechecked, to help avoid false
44						events.  This value is affected by the
45						material used to build the touch layer
46						(u16).
47		ti,x-plate-ohms			Resistance of the X-plate,
48						in Ohms (u16).
49		ti,y-plate-ohms			Resistance of the Y-plate,
50						in Ohms (u16).
51		ti,x-min			Minimum value on the X axis (u16).
52		ti,y-min			Minimum value on the Y axis (u16).
53		ti,x-max			Maximum value on the X axis (u16).
54		ti,y-max			Minimum value on the Y axis (u16).
55		ti,pressure-min			Minimum reported pressure value
56						(threshold) - u16.
57		ti,pressure-max			Maximum reported pressure value (u16).
58		ti,debounce-max			Max number of additional readings per
59						sample (u16).
60		ti,debounce-tol			Tolerance used for filtering (u16).
61		ti,debounce-rep			Additional consecutive good readings
62						required after the first two (u16).
63		ti,pendown-gpio-debounce	Platform specific debounce time for the
64						pendown-gpio (u32).
65		pendown-gpio			GPIO handle describing the pin the !PENIRQ
66						line is connected to.
67		linux,wakeup			use any event on touchscreen as wakeup event.
68	
69	
70	Example for a TSC2046 chip connected to an McSPI controller of an OMAP SoC::
71	
72		spi_controller {
73			tsc2046@0 {
74				reg = <0>;	/* CS0 */
75				compatible = "ti,tsc2046";
76				interrupt-parent = <&gpio1>;
77				interrupts = <8 0>;	/* BOOT6 / GPIO 8 */
78				spi-max-frequency = <1000000>;
79				pendown-gpio = <&gpio1 8 0>;
80				vcc-supply = <&reg_vcc3>;
81	
82				ti,x-min = /bits/ 16 <0>;
83				ti,x-max = /bits/ 16 <8000>;
84				ti,y-min = /bits/ 16 <0>;
85				ti,y-max = /bits/ 16 <4800>;
86				ti,x-plate-ohms = /bits/ 16 <40>;
87				ti,pressure-max = /bits/ 16 <255>;
88	
89				linux,wakeup;
90			};
91		};
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