KOE LVDS Capacitive Display Set

This section shows information about the KOE LVDS Capacitive Display Set. The iMX8M Industrial Development Kit in this configuration is equipped with Yocto dunfell, kernel 5.4 to support LVDS display with a touchscreen layer. In this case the display is installed on the top of the iMX8M Development Baseboard.

Mechanical connection

When combined with the complete iMX6 Rex Development Kit, the iMX6 Rex Display Set creates a compact, ready-to-use solution. To assemble them together, the following mechanical and electrical accessories were designed and selected to be part of the Display set:

TFT EDT display with LVDS interface and resistive touchscreen
H-shaped auxiliary aluminum holder
display adapter board
flat flex 33-wire cable, 127mm long
20-wire display + touchscreen cable
necessary connectors, screws, nuts and spacers
touch pen

Hardware connection

To enable smooth communication between the board and the display, iMX6 Rex Adapter was designed to connect the set together. To implement the display capabilities, following connections need to be made:

connection between LVDS Display and LVDS Adapter J1 (using a flexible flat cable)
LVDS Interface and power connection between iMX6 Rex Development Kit J41 and LVDS Adapter J2 (using LVDS and Touchscreen cable)
touchscreen connection between iMX6 Rex Development Kit J40 and LVDS Adapter J3 (using LVDS and Touchscreen cable)

LVDS and Touchscreen cable

Software instructions

iMX6 Rex Display Set is preinstalled with Android operation system enabling LVDS and touchscreen capabilities by default. Manual configuration is not necessary, but might be useful in individual cases.

LVDS manual booting

Manually booting with LVDS interface as a primary source for video output:

Rex U-Boot > setenv video 'video=mxcfb0:dev=ldb,edt570,if=RGB666 video=mxcfb1:off'
Rex U-Boot > boot

Touchscreen test

Make sure TSC2007 chip is detected and bound as input device:

root@imx6-rexultra:~# dmesg | grep -i tsc2007
input: TSC2007 Touchscreen as /devices/soc0/soc.0/2100000.aips-bus/21a4000.i2c/i2c-1/1-0048/input/input0
evbug: Connected device: input0 (TSC2007 Touchscreen at 1-0048/input0)

Touchscreen events are generated after pressing the resistive layer:

root@imx6-rexultra:~# evtest /dev/input/by-path/platform-21a4000.i2c-event 
Input driver version is 1.0.1
Input device ID: bus 0x18 vendor 0x0 product 0x0 version 0x0
Input device name: "TSC2007 Touchscreen"
Supported events:
  Event type 0 (EV_SYN)
  Event type 1 (EV_KEY)
    Event code 330 (BTN_TOUCH)
  Event type 3 (EV_ABS)
    Event code 0 (ABS_X)
      Value   3529
      Min        0
      Max     4095
    Event code 1 (ABS_Y)
      Value    375
      Min        0
      Max     4095
    Event code 24 (ABS_PRESSURE)
      Value      0
      Min        0
      Max     4095
Properties:
Testing ... (interrupt to exit)
Event: time 1457899907.959665, type 1 (EV_KEY), code 330 (BTN_TOUCH), value 1
Event: time 1457899907.959665, type 3 (EV_ABS), code 0 (ABS_X), value 1657
Event: time 1457899907.959665, type 3 (EV_ABS), code 1 (ABS_Y), value 2486
Event: time 1457899907.959665, type 3 (EV_ABS), code 24 (ABS_PRESSURE), value 3268
Event: time 1457899907.959665, -------------- EV_SYN ------------
Event: time 1457899907.969094, type 1 (EV_KEY), code 330 (BTN_TOUCH), value 0
Event: time 1457899907.969094, type 3 (EV_ABS), code 24 (ABS_PRESSURE), value 0
Event: time 1457899907.969094, -------------- EV_SYN ------------