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Contents
Touchscreen interfaceEdit
DescriptionEdit
The Touchscreen interface is available on the Evaluation Kit at the connector J20
J20 is a 6 pin Molex PicoBlade connector for the I2C and control signals needed by most of the capacitive TSC.
This interface can be configured to work with 3.3V (default) or 5V power and signal levels.
SignalsEdit
The following table describes the interface signals:
| Pin# | SOM Pin# | Pin name | Pin function | Pin Notes |
|---|---|---|---|---|
| 1 | - | DGND | Ground | |
| 2 | J18.48 | TOUCH_SDA | I2C_SDA | |
| 3 | J18.38 | TOUCH_SCL | I2C_SCL | |
| 4 | J18.101 | TOUCH_VDD | TSC power | powered through a control switch |
| 5 | J18.201 | TOUCH_INT | TSC interrupt | input |
| 6 | J18.199 | TOUCH_RES | TSC reset | output |
Device mappingEdit
The device is typically mapped to /dev/touchscreen0 device in Linux.
The touch controller is attached to the generic Linux input event interface (evdev).
Device usageEdit
The simplest tools for touch screen management are the tslib library and ts_tools utilities. To calibrate the touch screen, the ts_calibrate command line tool is available. After calibration, the touch screen can be tested using the graphical ts_test utility or the ts_print command line tool.