22-01-2019 | | By Nnamdi Anyadike
Display interface technology is everywhere today, from the small coffee machine to the big stadium screen. However, with the advent of 5G and the internet enabled home it is set to become even more ubiquitous. Essentially, an interface is a shared boundary across which two separate components of a computer’s system exchange information. All displays work in a similar manner with many rows and columns of pixels. These are driven by a controller that communicates with each pixel to emit the brightness and colour needed to make up the transmitted image.
According to US Micro Products the developer and designer of custom display solutions, pixels can either be diodes that light up when current flows (PMOLEDs and AMOLEDs). Alternatively, they can act as a shutter to let some of the light from a backlight visible. In every case, a memory array stores the image information that travels to the display through an interface. The number of different types of display interfaces include: Serial Peripheral Interface (SPI), Inter-integrated Circuit (I2C), RGB (Red Green Blue), Low-voltage Differential Signalling (LVDS) and Mobile Industry Processor Interface (MIPI).
SPI that was developed by Motorola for components to share data such as flash memory is a synchronous serial communication interface that is best-suited for short distances. It is a great option for small, low-resolution displays including PMOLEDs and smaller LCDs and has the advantage of speed over the I2C display interface. The I2C developed by Philips Semiconductors for simple peripherals on PCs, like keyboards and mice then later applied to displays utilises a multi-master, multi-slave, single-ended, serial computer bus system. Like SPI, it works best over short distances. What sets it apart from SPI is that it can support up to 1008 slaves and only requires two wires, a serial clock (SCL), and serial data (SDA).
RGB is used to interface with large colour displays. This interface can drive much larger displays at video frame rates of 60Hz and up. It has the benefits of low cost and high performance. LVDS are a popular choice for large LCDs and peripherals in need of high bandwidth, like high-definition graphics and fast frame rates. It has a high speed of data transmission while using low voltage. The interface consists of four, six, or eight pairs of wires, plus a pair carrying the clock and some ground wires.
MIPI is a newer technology that is managed by the MIPI Alliance. It has become a popular choice among wearable and mobile developers. MIPI supports a complex protocol that allows high speed and low power modes, as well as the ability to read data back from the display at lower rates. At the end of 2018, the MIPI Alliance released its I3C basic interface specification for widespread implementation in mobile and beyond. It provides a streamlined upgrade path from I2C.
Commenting on the array of display interfaces available, Rudolf Sosnowsky, CTO of HY-LINE Computer Components GmbH the application specialist in the fields of display technology, embedded computing, signal management and transfer questioned, “Is there an 'ideal' interface for displays? Probably not...they need to be selected, according to the application requirements for bandwidth and other aspects.” The company will be presenting at this year's ‘Electronic Displays’ conference, which will take place in February at ‘Embedded World 2019’ in Nuremberg.
A major player in the display market is Tokyo based THine Electronics Inc., the global leader in high-speed serial interface and provider of mixed-signal LSI. Recently, it introduced its 4x10Gbps CML redriver product for 2x4K XR (AR/VR/MR) active cable solutions. The product has 4-channel signal conditioning function for high-speed 10Gbps interfaces such as USB3.2, USB3.1Gen2, Thunderbolt, and DisplayPort1.3. Yasuhiro Takada, CEO of THine Electronics said, “This 4x10Gbps redriver enables smarter data transmission not only for PC and mobile devices but also suitable for XR devices with 4K resolution per eye through thinner/flexible, longer active cables with less-expensive materials.”
At the heart of every electronic device is embedded computing. And recently, Estone Technology introduced its EMB-7610 Apollo Lake embedded board. The EMB-7610 is a proprietary form factor board, 160mm x 90mm, designed especially for Digital Surveillance, In-Vehicle Electronics, Industrial Automation, Retail and Medical Technologies. Display Options include: 1x LVDS/eDP, 1x MIPI-DSI and 1x Micro-HDMI Port (Up to 1920x1200).
The 24bit LVDS, eDP or MIPI, power, backlight controls, and touch panel interfaces for screens have all been located in a single FPC connector for integration with all types of industrial and touch panel PC applications. The Intel processor supports a MIPI-CSI input and MIPI-DSI output, integrated audio inputs and outputs, as well as up to 3 independent displays in sizes from 7” to 10.1” or more. An example of a panel PC built with the EMB-7610 board is already available from Estone Tech – the PPC-6710.
Another recent unveiling is from Axiomtek. In January, it announced the launch of its CAPA84R fanless 3.5-inch embedded motherboard that is powered by the Intel Celeron processor J1900 quad-core or J1800 dual-core. The 3.5-inch embedded SBC with the Intel integrated Gfx graphics is made to bring a high definition visual experience with dual display configurations through the DisplayPort, 18/24-bit dual-channel LVDS and VGA.