SBC Axel SBC/Interfaces and Connectors/LVDS

History
ID#	Issue Date	Notes
14549	22/09/2021	First DESK release

LVDS

Description

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

The following tables describes the interface signals

LVDS0

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

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

• 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

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

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

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

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

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