How to setup and use LVDS Type TFT-LCD on SP7021 EV Board

Owned by hammer.hsieh
Last updated: Jul 08, 2021
2 min read

SP7021 LVDS Type TFT-LCD Support List

SP7021 EV board + adapter board + (TFT-LCD panel with LVDS interface)

Such as

ILLUMINANT 3.97” LVDS panel ILL-397015A 1280x720

Hardware Connect between SP7021 and TFT-LCD panel

1) Main Board :

SP7021 only support TTL RGB 24-bits module directly.

In case of LVDS type TFT-LCD panel, it needs an adapter for converting TTL signal to LVDS signal.

2) TFT-LCD panel:

If you get a TFT-LCD panel with LVDS interface, then you have to make an adapter board for it including TTL-to-LVDS IC .

3) Adapter Board (Main Board connect to TFT LCD):

    To make an adapter board, it needs hardware skills.

 

    For example

ILLUMINANT 3.97” LVDS panel ILL-397015A 1280x720

Adapter board reference design (See attached pdf file for your reference)

  •     5V to 3.3V power circuit (it depends on TFT-LCD panel maker)

  •     SPI interface for sending TFT-LCD panel initialization parameters(it depends on TFT-LCD panel maker).

  •     TFT-LCD panel backlight power circuit (it depends on TFT-LCD panel maker).

  •     TFT-LCD panel LCM bias power circuit (it depends on TFT-LCD panel maker).

  •     TTL-to-LVDS IC for convert SP7021 TTL signal to TFT-LCD LVDS signal.

TTL-to-LVDS IC have been confirmed TI DS90C383BMT/ TI DS90C385AMT / THC63LVDM83D, all of these 3 IC work fine.

Software Configuration for TFT-LCD panel

Due to TFT-LCD function use a lot of pins , most SP7021 based PCB design choose not to support it. If you choose to use TFT-LCD , many default function must disable or shift some default function pinout to other place.

Uboot Display driver enable setting

This panel didn’t initialize necessary parameters itself, so we do it in uboot.

Kernel Display driver dts setting

   Copy ./linux/kernel/arch/arm/boot/dts/sp7021-ev-ttl.dts all content

   to   ./linux/kernel/arch/arm/boot/dts/sp7021-ev.dts

#define ENABLE_TTL_1280X720

 

System Application on linux OS