Bridge of SPIs …



…also D-PHYs, Dual D-PHYs, sub-LVDS, and more. A new device—programmable ASSP— takes on connectivity challenges.

Just before the launch of Lattice Semiconductor’s CrossLink™, a programmable bridging device, Subra Chandramouli, the company’s Director of Marketing, Mobile and Consumer, spoke with EECatalog about the bridge and about both the traditional and nascent markets Lattice is targeting.

EECatalog: What are some of the challenges your programmable ASSP is tackling?

Subra Chandramouli, Lattice Semiconductor: The pace of innovation continues to rapidly increase with the proliferation of low cost image sensors and displays. Today these mobile components lie at the heart of new innovations not only in smartphones and tablets, but also DSLR cameras, drones, virtual reality (VR) systems, medical tools and industrial displays. In addition, components originally designed for the mobile market are being used in traditional industrial markets. In many cases, devices in the system don’t often interface to each other directly. Often the interface type or number of interfaces on the applications processor does not match those on the system’s image sensors or displays. Today’s embedded video designers need high performance, low power and compact interface bridges that can easily resolve these connectivity problems in a manner that maximizes design flexibility and spurs design innovation. Ideally they need a CrossLink bridging solution that can:

  • Convert incompatible interfaces between cameras, displays and processors
  • Combine multiple video stream inputs into a single interface output
  • Split video streams into multiple interfaces

EECatalog: What are some of the advantages of a pASSP™ solution?

Chandramouli, Lattice Semiconductor: The CrossLink device combines the flexibility and fast time to market of an FPGA with the power and functional optimization of an ASSP to create a new product class called programmable ASSP (pASSP) that delivers the best of both worlds. This low cost video interface bridge offers the highest bandwidth, lowest power and smallest footprint. This makes it ideal for a variety of applications such as virtual reality (VR) headsets, drones and DSLR cameras to smartphones, tablets and wearable devices.

EECatalog: Could you describe a couple of CrossLink use cases?

Chandramouli, Lattice Semiconductor: In today’s VR headsets, designers often need to convert incoming video from a single MIPI DSI interface and split it out over two MIPI DSI interfaces at half the bandwidth. How does the designer support these types of applications if the application processor only has a single DSI interface or one of its available DSI interfaces is being used for another function?

One way to solve this problem is to use a CrossLink device as a single MIPI DSI to Dual MIPI DSI bridge. Here the CrossLink  bridge receives the DSI data, splitting it into two, and drives two displays, using two DSI ports, as shown in Figure 1. The DSI ports driving the displays will be at half the bandwidth of the data coming in from the application processor. CrossLink can support two HD displays at I/O rates up to 1.5 Gbps/lane.

Figure 1: Driving two displays using the DSI protocol. (Courtesy Lattice Semiconductor)

Figure 1: Driving two displays using the DSI protocol. (Courtesy Lattice Semiconductor)

Another example from the industrial market would be a Human Machine Interface (HMI] application (Figure 2). MIPI D-PHY based displays, originally designed for use in mobile consumer markets, are being used by designers building systems for the industrial market. Designers prefer using their existing application processor that may support a legacy CMOS interface to drive displays. In such situations, CrossLink may be used to bridge between the legacy CMOS interface and the D-PHY display, as shown in Figure 3.

Figure 2: Medical and industrial applications relying on an effective Human Machine Interface (HMI) are among those which could benefit from the availability of CrossLink to bridge, for example, a legacy CMOS interface to a D-PHY display. (Courtesy Lattice Semiconductor)

Figure 2: Medical and industrial applications relying on an effective Human Machine Interface (HMI) are among those which could benefit from the availability of CrossLink to bridge, for example, a legacy CMOS interface to a D-PHY display. (Courtesy Lattice Semiconductor)

Figure 3: Bridging CMOS data to a D-PHY display. (Courtesy Lattice Semiconductor)

Figure 3: Bridging CMOS data to a D-PHY display. (Courtesy Lattice Semiconductor)

In applications such as DSLR cameras, surveillance applications and drones, designers need to bridge between industrial image sensors and mobile application processors. Many of the industrial image sensors in these applications offer excellent performance, but use a legacy proprietary interface originally developed by the sensor manufacturer.

Designers building embedded applications in these markets typically want to leverage the tremendous innovations available on popular mobile application processors. In order to do this they need to convert the signal from those proprietary image sensor interfaces to a mobile MIPI CSI-2 image sensor interface found on most of today’s mobile application processors. Using its programmable fabric, the CrossLink device offers developers the ability to build compact, high performance, low power interface bridges that can convert a signal from those proprietary interfaces to MIPI CSI-2, as shown in Figure 4.

Figure 4: Bridging sub-LVDS to CSI-2. (Courtesy Lattice Semiconductor)

Figure 4: Bridging sub-LVDS to CSI-2. (Courtesy Lattice Semiconductor)

EECatalog: Any closing thoughts before we conclude?

Chandramouli, Lattice Semiconductor: The future looks promising for the embedded video systems market. Exciting new applications are coming to market ranging from VR and 3D video to new surveillance systems, smart homes, improved medical tools and industrial systems. One key to their success will be designers’ ability to continually improve performance and utility. CrossLink provides these designers the flexibility to choose the components that best suit their needs.

  • World’s fastest MIPI® D-PHY bridging device that delivers up to 4K UHD resolution at 12 Gbps bandwidth.
  • Supports popular mobile, camera, display and legacy interfaces such as MIPI D-PHY, MIPI CSI-2, MIPI DSI, MIPI DPI, CMOS, and sub-LVDS, LVDS and more.
  • Industry’s smallest package size with a 6 mm2 option.
  • Lowest power programmable bridging solution in active mode.
  • Built-in sleep mode.
  • Takes the strongest features from ASSPs and FPGAs to deliver the best solution of both worlds.
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