KOE LVDS Capacitive Display Set

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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.
iMX8M Industrial Dev Kit KOE LCD.jpg

Mechanical connection

When combined with the complete iMX8M Industrial Kit, the 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 LCD 1920 x 1080 Pixels display (TX18D200VM0EAA) with LVDS interface and Capacitive Touch with SIS9509 controller
  • 4x Hex Standoff Threaded M3 35.00mm long [Manufacturer PN: 971350321]
  • custom 20-pins LVDS cable, 180mm long. The cable is supply with LCD as set
  • custom 2-pins cable for LCD back light, 150mm long. The cable is supply with LCD as set
  • necessary spacers

iMX8M Industrial Dev Kit KOE LCD Side view.jpg

Hardware connection

To enable smooth communication between the board and the display, connect the 20 Position LVDS cable for LCD and 6 pin touchscreen FFC cable. To implement the display capabilities, following connections need to be made:

  • connection between LVDS Display and iMX8M Development Baseboard connector LVDS0 KOE (J14) using a 20 Position LVDS cable
  • 2 position back light cable connect to connector J15
  • touchscreen connection between iMX8M Development Baseboard connector KOE Touch (J40) and Touchscreen 6 pin FFC cable

LVDS and Touchscreen cable

imx8m LVDS with touchscreen cable for KOE.jpg

Hardware jumpers KOE LVDS

Make sure that configurable 0R resistor are moved to KOE LVDS0 interface
LVDS0 KOE jumpers.png

Software instructions

iMX8M Industrial kit is preinstalled with Yocto dunfell operation system enabling LVDS and touchscreen capabilities by default. Manual configuration is necessary, Devicetree in U-Boot have to by set to KOE LVDS0 LCD.

LVDS0 KOE Devicetree in U-Boot

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

Fastboot: Normal
Normal Boot
Hit any key to stop autoboot:  0
u-boot=> fatls mmc 0:1
 27787776   Image
    48586   imx8mq-evk-voipac-dp.dtb
    48793   imx8mq-evk-voipac-hdmi.dtb
    49194   imx8mq-evk-voipac-lvds-koe.dtb
    49198   imx8mq-evk-voipac-lvds-newhaven.dtb

5 file(s), 0 dir(s)

u-boot=> setenv fdt_file imx8mq-evk-voipac-lvds-koe.dtb
u-boot=> saveenv
Saving Environment to MMC... Writing to MMC(0)... OK
u-boot=> boot

Touchscreen test

Default Voipac iMX8M Image contain evtest utility to catch touchscreen events. Make sure SiS9509 controller is detected and bound as input device:

root@imx8mq-voipac:~# dmesg | grep -i SiS9509 
input: ----------
evbug: ----------

ouchscreen events are generated after touching capacitive touch screen.

root@imx8mq-voipac:~# evtest /dev/input/by-path/platform-21a4000.i2c-event