SBC Axel SBC/Interfaces and Connectors/LVDS

From DAVE Developer's Wiki
Jump to: navigation, search
History
Version Issue Date Notes
1.0.0 Oct 2020 First DESK release


LVDS[edit | edit source]

Description[edit | edit source]

SBCX provides two LVDS interfaces, LVDS0 and LVDS1.

  • J8 is a Hirose (cod. DF13A-20DP-1.25V) double row 1.25mm pitch miniature crimping connector
  • J9 is a Hirose (cod. DF13A-20DP-1.25V) double row 1.25mm pitch miniature crimping connector


LVDS connectors

Signals[edit | edit source]

The following tables describes the interface signals

LVDS0[edit | edit source]

Pin# SOM Pin# Pin name Pin function Pin Notes
1, 2 - 3.3V_LCD0 3.3 V
3, 4, 7, 10,

13, 16, 19

- DGND Ground
5 J10.137 LVDS0_TX0_N LVDS Data 0 -
6 J10.139 LVDS0_TX0_P LVDS Data 0 +
8 J10.141 LVDS0_TX1_N LVDS Data 1 -
9 J10.143 LVDS0_TX1_P LVDS Data 1 +
11 J10.145 LVDS0_TX2_N LVDS Data 2 -
12 J10.147 LVDS0_TX2_P LVDS Data 2 +
14 J10.133 LVDS0_CLK_N LVDS Clock -
15 J10.135 LVDS0_CLK_P LVDS Clock +
17 J10.149 LVDS0_P17 Mount options LVDS0_TX3_N option
18 J10.151 LVDS0_P18 Mount options LVDS0_TX3_P option
20 J10.46 LVDS0_P20 Mount options GND or PWM (J10.46) option

LVDS1[edit | edit source]

Pin# SOM Pin# Pin name Pin function Pin Notes
1, 2 - 3.3V_LCD0 3.3 V
3, 4, 7, 10,

13, 16, 19

- DGND Ground
5 J10.159 LVDS1_TX0_N LVDS Data 0 -
6 J10.161 LVDS1_TX0_P LVDS Data 0 +
8 J10.163 LVDS1_TX1_N LVDS Data 1 -
9 J10.165 LVDS1_TX1_P LVDS Data 1 +
11 J10.167 LVDS1_TX2_N LVDS Data 2 -
12 J10.169 LVDS1_TX2_P LVDS Data 2 +
14 J10.155 LVDS1_CLK_N LVDS Clock -
15 J10.157 LVDS1_CLK_P LVDS Clock +
17 J10.171 LVDS1_P17 Mount options LVDS1_TX3_N option
18 J10.173 LVDS1_P18 Mount options LVDS1_TX3_P option
20 J10.46 LVDS1_P20 Mount options GND or PWM (J10.46) option

Device mapping[edit | edit source]

  • LVDS0 is mapped to /dev/fb0 device in Linux
  • LVDS1 is mapped to the corresponding device driver in Linux, depending on the ldb peripheral configuration in the device tree. The default value is disabled but can be mapped to /dev/fb2 (second and independent LCD panel) or can be the second LVDs channel for a dual-channel LCD panel configuration (like a 1920x1080 DUAL LVDS channel LCD panel)

Power sequence[edit | edit source]

Most of the LCD panels have many supplies and need a specific timing to power the rails and start the signals.

The Evaluation Kit provides GPIO controlled power rails that can be leveraged both at bootloader and kernel level to meet any specifications.

The following sections describe the available rails:

3V3_LCD[edit | edit source]

The most common voltage to supply the LCD panel internal logic:

  • rail 3V3_LCD0 is enabled by GPIO1_IO00
  • rail 3V3_LCD1 is enabled by GPIO1_IO02

5V_LCD[edit | edit source]

The most common voltage to supply the LCD panel backlight:

  • rail 5V_LCD0 is enabled by SD3_DATA1
  • rail 5V_LCD1 is enabled by SD3_DATA0

Device usage[edit | edit source]

The associated framebuffer device is accessed in Linux through the standard graphic access.