Most laptops, tablet computers, flat-panel monitors, and TVs use this interface internally. National Semiconductor immediately provided connectors in fpd pdf specifications for the FPD-Link technology in order to promote it as a free and open standard, and thus other IC suppliers were able to copy it.
TI was the first interoperable version of FPD-Link. There have been numerous attempts to displace FPD-Link as the standard internal video interface in mobile devices and LCD TVs. FPD-Link as an internal interface. The reason for FPD-Link’s resilience is its simplicity and the low cost of implementation.
This reduces the radiated emissions. The reduced vulnerability to electrical noise interference comes from the fact the noise affects both signals commonly. Since the LVDS receiver senses the difference between the two commonly affected signals, it senses no impact from the common mode noise. The FPD-Link data transmission scheme serializes seven single-ended data bits per clock cycle into each of the LVDS channels. Therefore, the LVDS bit rate is 7 times the frequency of the clock signal. For example, in the 18-bit RGB application, there are 6 bits each for R, G, and B and an additional 3 bits for horizontal and vertical synch and an enable signal. This means there are 21 total data signals in each clock cycle, which means the 7 to 1 serialization reduces this down to 3 data channels.
This same scheme scales to 24-bit and 30-bit color in the following manner. 28-bit input down to 4 pairs plus the clock, which is perfect for 8-bits per RGB plus 4 video control bits. C FPD-Link interface serializes 35-bits per clock cycle, which is 10-bits per RGB plus 5 video control bits. Automotive infotainment displays for navigation systems started using FPD-Link in 2001. BMW was the first car maker to use FPD-Link in their cars for transferring navigation graphics from the head unit to the central information display. Many other car manufacturers then started using FPD-Link. Today, most infotainment and driver assist applications are using FPD-Link II and FPD-Link III to benefit from the embedded clock and control signals, which will be described in the next section.
One of the main benefits is the reduced cable size and weight due to the single wire pair for all the data and clock signals. The automotive environment is known to be one of the harshest for electronic equipment due to inherent extreme temperatures and electrical transients. In order to satisfy these stringent reliability requirements, the FPD-Link II and III chipsets meet or exceed the AEC-Q100 automotive reliability standard for integrated circuits, and the ISO 10605 standard for automotive ESD applications. Sometimes the OpenLDI and FPD-Link terms are used interchangeably. In the Open LDI version of DC balance coding, one of the seven serialized bits indicates whether the coding scheme needs to invert the other six bits transmitted in the clock period to maintain DC balance. Therefore, each LVDS pair other than the clock pair effectively transmits six bits per clock cycle. DVI to receive video from a desktop computer.
2006 and is an improved version of FPD-Link. National Semiconductor designed it specifically for automotive infotainment and camera interface applications. FPD-Link II embeds the clock in the data signal and therefore uses only one differential pair to transmit both the clock and video data. This further reduces the size, weight, and cost of cables for infotainment and safety camera applications. For example, the 24-bit color application now uses only one twisted pair instead of the 5 twisted pair used by FPD-Link.
There are additional benefits from FPD-Link II. For example, the car makers appreciate the increased cable length even with reduced cable cost. This is because of the embedded clock feature that eliminates the timing skew between clock and data signals. This was the limiting factor to cables with separate clock and data pairs because all pairs had to be manufactured at precisely equal length to control the timing skew between the clock and data pairs. This length matching added to the cable cost. Another benefit for FPD-Link II comes from adding DC balance to the signals.
This is critical in the automotive applications because of the potential for large transient currents that can damage sensitive electronic equipment. The higher resolution applications required FPD-Link II to increase the data throughput. But for the applications that required up to 1. LVDS was not as reliable as necessary for the automotive applications. FPD-Link II chipsets were able to reliably send high bit-rate video streams over cables longer than 10m. Further improving FPD-Link II, FPD-Link III’s major feature is embedding a bidirectional communication channel on the same differential pair.
This bidirectional channel transfers control signals between source and destination in addition to the clock and streaming video data. FPD-Link III’s embedded control channel uses the I2C bus protocol between the source and destination in the first implementations. However, it is not limited to I2C. The I2C master can read and write to all the slaves on the other side of the FPD-Link III chipset, which is effectively transparent to the I2C master and slaves communications. For example, this enables infotainment head units to control and configure displays, and image processing units to control and configure cameras using the same twisted pair cable as the data transmission. This approval enables the FPD-Link III chipsets to include the highly confidential HDCP keys and state machines to encrypt the content.