Difference between revisions of "LVDS2HD"

Revision as of 17:59, 10 February 2026

LVDS2 Front

LVDS2 Back

LVDS2 PCB Layout

LVDS2

LVDS2 with Cable

Overview

Due to the wide variety of screens on the market, the EDID recognition of different screens may have compatibility issues, which may lead to incorrect screen colors or abnormal screens or no display.

This LVDS2HD board convert LVDS input signal to HDMI output, the resolution is VESA standard in default. If you need change to single 8 mode, please short the R20 on the LVDS2HD board.

Because it is the DIY product, so sometimes there may be the compatibility problem. When it shows no signal or no sound, it may be the compability problem.

Features

LVDS input signal to HDMI output, the maximum bandwidth can reach 150MHz;
LVDS input interface adopts the general 30-pin socket FI-X30SSLA-HF, which supports dual 8 inputs, and the riginal screen cable can be used directly;
Double 8 mode in default
I2S sound input in default
VESA standard resolution in default
8bit in default
Not only supports standard HDMI signals, but also supports other graphics format signals, the common formats are as follows: 1920x1200, 1920x1080, 1600x1200, 1280x1024, 1280x720, etc.
Support LVDS signal to spread spectrum
Input Voltage Range:DC 4.8V～5.5V, Powered by 5V in the screen cable

Packing List

1 x LVDS to HDMI Converter with Cable (cable length: 22cm)

User Manual

Dimensions source file (DXF): File:HDMI2LVDS-PCBLayout.dxf - You can view it with Autodesk Viewer online

CN3/CN4/CN6 Interface Definition

How to Change the Mode

Debugging Notes

1. There are two LEDs on the board. After power-on, D1 blinks indicating the MCU is working properly. D2 stays on when the LVDS signal is received. If D2 does not light up, it means no LVDS signal is received - - check the wire sequence.

2.Before power-on, first confirm if LVDS is single-channel or dual-channel. Normally, 1080P signal is dual-channel, while 720P, 1366x768, 1024x768 and other resolutions are single-channel. For single-channel, short-circuit R20 on the board before powering on. (DIP switch (J1) can be installed for easier debugging.)

3.If D2 fails to light up and there’s no HDMI output after power-on, the possible causes are:

(1)Incorrect single/dual-channel configuration (R20);

(2)Mismatched LVDS wire sequence;

(3)Short-circuit R21 and retest (for VESA/JEIDA mapping);

(4)Differential pair polarity (+/−) reversed (Fix: First swap only O2+/O2− and OCLK+/OCLK−. If D2 lights up after swapping, polarity is correct; then swap all remaining twisted pairs).

Double-check to ensure correct wiring and configurations.

4.If D2 stays on with stable LVDS signal reception but the monitor still shows a black screen, verify if the monitor supports the current LVDS output resolution. HDMI signals are standard video formats (e.g., 1080P, 720P), and some TVs do not support non-standard resolutions such as 1366x768. In this case, convert the HDMI output to a DVI interface and input the signal via the monitor’s DVI port.

5.If D2 flashes on and off, the issue may be caused by an excessive spread spectrum amplitude of the LVDS signal. While this solution supports clock spread spectrum, it has a certain amplitude limit – the LVDS signal cannot be received stably if the limit is exceeded. If the motherboard configuration is modifiable, disable the LVDS signal spread spectrum and retest.

6.If soldering is needed for testing due to mismatched connectors, differential pairs (+/–) must use twisted pairs, not loose wires.

7.If the cause cannot be identified, connect RX and GND of a USB-to-UART cable (typically CH340G) to TX and GND of CN1 on the board to view debug information, as shown below.

If the debug print scrolls continuously, the cause is definitely unstable LVDS signals, resulting in changes to the 5 parameters shown above:

(1)Ensure LVDS differential pairs use twisted pairs and are free from interference.

(2)If InputPclk fluctuates, check if SSC (Spread Spectrum Clocking) is enabled; disable it for testing if possible.

(3)If HTotal or VTotal fluctuates, check the synchronization mode in software settings (usually Freerun or FrameLock). For LVDS-to-HDMI output, the mode must be Freerun with fixed HTotal/VTotal. For direct LVDS display, HTotal/VTotal may vary within a limited range without affecting the image. Thus, LVDS working for direct display does not guarantee valid LVDS-to-HDMI output.

8.If stable timing is observed via the serial port but still no HDMI output, use a multimeter to check the DC level at the HDMI output port, as shown below:

If the voltages on the 8 pins of the HDMI connector and the lower end of R31 (refer to the figure) are within the normal range, but the connected monitor still shows no image, the monitor may not support this resolution. TV HDMI ports usually support 720P, 1080P, etc., and do not support graphics card resolutions such as 1024×768 or custom arbitrary resolutions. If the LVDS output resolution is 1024×768 or similar, test with the monitor’s DVI port using an HDMI-to-DVI cable.

If the multimeter shows abnormal voltage on any pin in the figure, first verify the HDMI cable. If the cable is good, the board hardware is faulty, likely damaged by static electricity.

FAQ

Q1: After screen replacement, no HDMI output, but the indicators (D1 flashing, D2 solid) are functioning normally?

Log Information - click it to zoom out

A:Please print the log information as instructed (Refer to the image)

-Connect the board's TX and GND to the PC via a USB-to-UART TTL cable. Set baud rate to 115200 and monitor for debug messages

Enable comment auto-refresher

Anonymous user #31

4 days ago

Score 0

New update from RUBY help me lot, I add 1K to R30 and HDMI out work fine.

For all you need tested to 12v Mainboard TV is just only add DC-DC convert in the input of this board …

@@ Line 37: / Line 37: @@
 [[File:LVDS2-06.jpg|700px|LVDS2 Mode Selection]]
-'''D1&D2 LED Indicator'''
+----
+'''Debugging Notes'''
-After power on, D1 flashes,it indicates that the MCU is working normally. After receiving the LVDS signal, D2 is always on.
+. There are two LEDs on the board. After power-on, D1 blinks indicating the MCU is working properly. D2 stays on when the LVDS signal is received. '''If D2 does not light up, it means no LVDS signal is received - - check the wire sequence.'''
-If D2 is not light on, it means that no LVDS signal is received, and the line sequence needs to be checked.
+[[File:LVDS2-07.png|700px|On-board LED]]
-[[File:LVDS2-07.png|700px|LVDS2]]
+.Before power-on, first confirm if LVDS is single-channel or dual-channel. Normally, 1080P signal is dual-channel, while 720P, 1366x768, 1024x768 and other resolutions are single-channel. For single-channel, short-circuit R20 on the board before powering on. (DIP switch (J1) can be installed for easier debugging.)
+[[File:On-board Option Resistors.png|700px|On-board Option Resistors]]
+.If D2 fails to light up and there’s no HDMI output after power-on, the possible causes are:
+(1)Incorrect single/dual-channel configuration (R20);
+(2)Mismatched LVDS wire sequence;
+(3)Short-circuit R21 and retest (for VESA/JEIDA mapping);
+(4)Differential pair polarity (+/−) reversed (Fix: First swap only O2+/O2− and OCLK+/OCLK−. If D2 lights up after swapping, polarity is correct; then swap all remaining twisted pairs).
+'''Double-check to ensure correct wiring and configurations.'''
+.If D2 stays on with stable LVDS signal reception but the monitor still shows a black screen, verify if the monitor supports the current LVDS output resolution. HDMI signals are standard video formats (e.g., 1080P, 720P), and some TVs do not support non-standard resolutions such as 1366x768. In this case, convert the HDMI output to a DVI interface and input the signal via the monitor’s DVI port.
+.If D2 flashes on and off, the issue may be caused by an excessive spread spectrum amplitude of the LVDS signal. While this solution supports clock spread spectrum, it has a certain amplitude limit – the LVDS signal cannot be received stably if the limit is exceeded. If the motherboard configuration is modifiable, disable the LVDS signal spread spectrum and retest.
+.If soldering is needed for testing due to mismatched connectors, differential pairs (+/–) must use twisted pairs, not loose wires.
+.If the cause cannot be identified, connect RX and GND of a USB-to-UART cable (typically CH340G) to TX and GND of CN1 on the board to view debug information, as shown below.
+[[File:LVDS2-EN.jpg|700px|Debug Information]]
+'''If the debug print scrolls continuously, the cause is definitely unstable LVDS signals''', resulting in changes to the 5 parameters shown above:
+(1)Ensure LVDS differential pairs use twisted pairs and are free from interference.
+(2)If InputPclk fluctuates, check if SSC (Spread Spectrum Clocking) is enabled; disable it for testing if possible.
+(3)If HTotal or VTotal fluctuates, check the synchronization mode in software settings (usually Freerun or FrameLock). For LVDS-to-HDMI output, the mode must be Freerun with fixed HTotal/VTotal. For direct LVDS display, HTotal/VTotal may vary within a limited range without affecting the image. Thus, LVDS working for direct display does not guarantee valid LVDS-to-HDMI output.
+.If stable timing is observed via the serial port but still no HDMI output, use a multimeter to check the DC level at the HDMI output port, as shown below:
+* If the voltages on the 8 pins of the HDMI connector and the lower end of R31 (refer to the figure) are within the normal range, but the connected monitor still shows no image, the monitor may not support this resolution. TV HDMI ports usually support 720P, 1080P, etc., and do not support graphics card resolutions such as 1024×768 or custom arbitrary resolutions. If the LVDS output resolution is 1024×768 or similar, test with the monitor’s DVI port using an HDMI-to-DVI cable.
+* If the multimeter shows abnormal voltage on any pin in the figure, first verify the HDMI cable. If the cable is good, the board hardware is faulty, likely damaged by static electricity.
+[[File:DC-level.jpg|700px|HDMI output DC level]]
 ==FAQ==

Difference between revisions of "LVDS2HD"

Revision as of 17:59, 10 February 2026

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Packing List

User Manual

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