How to quickly Identify Pin 1 of eDP Panel
When you purchase a 30-pin or 40-pin eDP panel, you'll need to use an eDP cable to connect to the LattePanda board. It's crucial to note that eDP cables have a specific pin orientation, and incorrect connections can damage the screen or even the board.
To determine the correct pinout, first, you need to identify which pin is pin 1 on the eDP panel connector.
Method 1: Look for the White Silkscreen Marking “1”
Usually, near the connector, there's a white silkscreen marking indicating pin 1. The outermost pin at the end of the connector with this marking is pin 1.
For example, in the picture above, the right side of the connector has a white silkscreen “1”, then the rightmost pin is pin 1.
Method 2: Determine Based on Trace Routing at the Connector
As seen in the diagram, which follows the VESA organization's Common 30-Pin Out for eDP Panel Connector, you can notice signal line names marked with _N and _P, such as Lane1_N and Lane1_P. “N” and “P” stand for Negative and Positive. These two signal lines form a differential pair.
In PCB design, differential pairs are controlled for equal length and impedance matching, hence they appear closely paired together in the following picture.
Based on these characteristics of differential pair routing, you can confirm the pin arrangement by identifying the differential pair traces at pins 3 and 4, 6 and 7, 9 and 10.
For example, in the following picture, starting from the rightmost side of the connector, you can clearly see the differential pair traces meeting the described criteria, confirming that the rightmost pin is pin 1.
Recommend a good website to check the pinout of various types of connectors: https://pinoutguide.com