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'''Debugging Notes'''
<mark>1. </mark> 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.'''
[[File:LVDS2-07.png|700px|On-board LED]]
<mark>2.</mark> 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]]
<mark>3.</mark> 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);
<mark>4.</mark> 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.
<mark>5.</mark> 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.
<mark>6.</mark> If soldering is needed for testing due to mismatched connectors, differential pairs (+/–) must use twisted pairs, not loose wires.
<mark>7.</mark> 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]]
<mark>8.</mark> 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.