LVDS panel settings: mapping, bit depth, ports
The LVDS settings in a TV firmware must match the panel exactly. The same cable can carry the data in different layouts, and a mismatch shows as odd colours, noise or a split picture. This article explains each setting and how to change it safely.
Part of the Panel settings guide. For symptoms see wrong panel settings.
The basics
- LVDS is a differential interface: data pairs plus one clock pair.
- 6-bit: 3 data pairs + 1 clock pair (4 pairs). 8-bit: 4 + 1 (5 pairs).
- A dual-channel panel (odd and even pixels, ports A and B) doubles the pair count: 8-bit uses 10 pairs, 10-bit uses 12.
- Connectors of 20 and 30 pins are normally single channel; 41 and 51 pins are dual channel and include panel power.
- 4K panels are usually V-by-One or eDP, not LVDS, so these settings do not apply to them.
The settings
Bit depth
Must equal the panel’s data width. A 6-bit panel driven in 8-bit mode (or the reverse) gives wrong levels or banding.
Channels and ports
Single or dual. If the halves of the image are swapped, the A and B ports are swapped; the program has a swap option.
Mapping: VESA or JEIDA
8- and 10-bit data can be placed on the lanes in two ways. Panels often have a select pin (named like SELLVDS or LVDS-SEL; check your panel’s datasheet for its logic levels). A wrong mapping gives strong colour and brightness distortion and noise in shadows.
Other options
Red/blue swap, MSB/LSB order, inversion, P/N polarity and mirroring exist as separate switches.
Step by step
- Get the panel datasheet: interface, pairs, bit depth, mapping pin state, supply voltage, resolution.
- Check the connector and the supply before connecting. A wrong supply (3.3, 5 or 12 V) can damage the panel.
- Set bit depth and channel count first, then the mapping.
- Look at a picture with a smooth gradient. Fix one parameter at a time and note the result.
- Only then touch the swaps (A/B, R/B, MSB/LSB) if symptoms remain.
Do not change several switches at once; you will not know which helped. Settings found by trial for one board may not apply to another with the same panel. UNVERIFIED The naming and meaning of mapping pins differ between panel makers; check against the datasheet.
Typical mistakes
- Matching panels only by connector and size.
- Applying the same settings after changing from 6-bit to 8-bit panel.
- Flashing a firmware without confirming that it holds the right panel entry (package structure).
- Using the old firmware’s settings after replacing the panel with a different model.
How this is done in FW Tool
- The “Adaptation” tab reads a supported firmware package and shows its current panel parameters.
- The “Screen” block lets you pick a panel from the package library or from your own
.ini, and set bit depth, number of LVDS channels, layout, A/B swap, red/blue, MSB/LSB, inversion, P/N and mirroring. - Settings can be saved and applied to several firmware files at once; the tab also handles the remote type and the boot logo.
- If the package lacks the panel file, the program warns that panel parameters cannot be edited.
- “Reference, LVDS and panels” holds the short guide used in this article. See features.
FAQ
Colours are inverted or too dark. Is it mapping?
Possibly; also check inversion. Change one switch at a time.
Can I use a panel with a different resolution?
The resolution is part of the panel entry too. Match interface, pairs, bit depth, supply and resolution.
Why does the picture have a seam in the centre?
Typical for dual-channel panels with swapped ports or the wrong channel setting.
Recording what works
When you find the correct combination for a panel, write it down together with the panel marking and the firmware version. Save the settings in the program so they can be applied again to another firmware of the same board. Panels with the same size and connector from different makers are common, so always record the exact marking from the panel’s label rather than only the diagonal.
If the picture is correct but the backlight or the image flickers, the cause is probably not in the LVDS settings at all; look at the supply and the cable. Settings change how data is interpreted, not whether the panel receives power.
One more point: after you change the firmware, give the TV time to apply the settings and perform a full power cycle, not just a standby. Some boards read the panel parameters only at the earliest stage of start-up, so a change can appear to do nothing until the next cold boot.