Lvds; Lvds Signals Description - Emerson COM Express Carrier Design Manual

8 LVDS

8.1 LVDS Signals Description

The COM Express specification provides an optional LVDS interface on the COM Express A-B connector.
Module pins for two LVDS channels are defined and designated as LVDS_A and LVDS_B. Systems use a
single-channel LVDS for most displays.
Dual LVDS channels are used for very high-bandwidth displays. Single-channel LVDS means that one
complete RGB pixel is transmitted per display input clock (also known as the shift clock; see Table 11
for a summary of LVDS terms).
Dual-channel LVDS means that two complete RGB pixels are transmitted per display input clock. The
two pixels are adjacent along a display line. Dual-channel LVDS does not mean that two LVDS displays
can be driven. Each COM Express LVDS channel consists of four differential data pairs and a differential
clock pair for a total of five differential pairs per channel. COM Express modules and module chipsets
may not use all pairs. For example, with 18 bit TFT displays, only three of the four data pairs on the
LVDS_A channel are used, along with the LVDS_A clock. The LVDS_B lines are not used. The manner in
which RGB data is packed onto the LVDS pairs (including packing order and color depth) is not
specified by the COM Express specification. This may be module-dependent. Further mapping details
are given in Table 11. There are five single-ended signals that are included to support the LVDS
interface. Two lines are used for an I
information and identification schemes. Additionally, there are LVDS power enable (LVDS_VDD_EN)
and backlight control and enable lines (LVDS_BKLT_CTRL and LVDS_BKLT_EN).
COM Express Carrier Type 2
Design Guide
2 C interface that may be used to support EDID or other panel
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