IoTGateway/BSP/Android/Gettingstarted/How to configure Capacitive Multi-touch Display

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Introduction

Because the standard to connect custom capacitive touch devices(single- or multi-touch) is not defined, this resulted in having a variety of touch drivers interface. General speaking, USB/HID and I2C are the common hardware interface.

Configure

  • HID interface

Enable HID in menuconfig 

Device Drivers --->
       Input device support --->
            <*> Event interface Miscellaneous devices --->
                  <*>User level driver support 
       HID Devices --->
            [*]/dev/hidraw raw HID device support Special HID drivers --->
                  <*> HID Multitouch panels 
  • I2C interface

Enable I2C bus in menuconfig 


Device drivers --->
        I2C support  --->
            <*> I2C support
                [*]   Enable compatibility bits for old user-space
                <*>   I2C device interface
                <*>   I2C bus multiplexing support
                        Multiplexer I2C Chip support  --->

copy and rename .config to arch/arm/configs/imx_v7_android_defconfig

Test

The getevent tool provides information about the touch device. 

# getevent -lt
[   78826.389007] EV_ABS       ABS_MT_TRACKING_ID   0000001f
[   78826.389038] EV_ABS       ABS_MT_PRESSURE      000000ab
[   78826.389038] EV_ABS       ABS_MT_POSITION_X    000000ab
[   78826.389068] EV_ABS       ABS_MT_POSITION_Y    0000025b
[   78826.389068] EV_ABS       ABS_MT_SLOT          00000001
[   78826.389068] EV_ABS       ABS_MT_TRACKING_ID   00000020
[   78826.389068] EV_ABS       ABS_MT_PRESSURE      000000b9
[   78826.389099] EV_ABS       ABS_MT_POSITION_X    0000019e
[   78826.389099] EV_ABS       ABS_MT_POSITION_Y    00000361
[   78826.389099] EV_SYN       SYN_REPORT           00000000
[   78826.468688] EV_ABS       ABS_MT_SLOT          00000000
[   78826.468688] EV_ABS       ABS_MT_TRACKING_ID   ffffffff
[   78826.468719] EV_ABS       ABS_MT_SLOT          00000001
[   78826.468719] EV_ABS       ABS_MT_TRACKING_ID   ffffffff
[   78826.468719] EV_SYN       SYN_REPORT           00000000

For developer mode option, showing touch points and locations on the screen 

Settings > Developer Options > Show touches
Settings > Developer Options > pointer location
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