Putting the Style in the Dial

Connected vehicles and more data for the driver mean that instrument clusters in the dashboard of medium to high-end vehicles are moving to digital, configurable, personalized displays.

The driving experience has moved beyond needing to know the speed of the vehicle, which was conveyed by a dial and a needle on the car dashboard. In today’s vehicles, drivers access information for a variety of uses. This can be the distance and directions to points of interest or practical vehicle information, such as remaining fuel. Or in the case of electric vehicles, battery information and when the next charge is due.

The analog displays of dial and needles are being replaced with a mix of analog and digital instrument clusters.

The Drive for Digital
The digital display is being used in a similar way to how consumers use notebooks, tablets, and smartphones. It can be programmed to display virtual instruments and configured to the driver’s preferences. In the Automotive Display Market Tracker, Principal Analyst, IHS Markit, Stacy Wu, identifies a shift from center stack and rear seat entertainment, to safety system displays in instrument clusters as well as heads-up displays, where data is displayed in front of the driver. Sales of safety-critical display panels are expected to experience double digit growth through 2022.

This could be a boon for display manufacturers who are seeing sluggish sales in mobile devices. “Stagnant panel demand from consumer electronics segments like notebooks, tablets, and smartphones, together with excess production capacity, is forcing display panel makers to enter the fast-growing automotive market,” observes Wu.

Figure 1: Cypress Semiconductor has added the S6J32xEK series to its Traveo automotive microcontroller family.

Today, pure digital displays can be found in high-end vehicles and some niche areas, including high-volume electric vehicles such as the Toyota Prius and Honda Civic. Used to provide in-vehicle network information and data from cameras and sensors, pure digital displays are more expressive. They can display color and graphics and evince clearer visibility in different light conditions. In addition, such displays can be programmed to show driver preferences or enable OEMs to differentiate vehicle interiors as a way to stand out in the competitive automotive sector.

Safety First

3D graphics convey more information to the driver. The connected vehicle means the driver can have access to data from cameras and sensors, as well as from the in-vehicle network of Electronic Control Units (ECUs) for status updates.

Take the case of 2D graphics for denoting tire pressure. Unlike 2D graphics, 3D graphics can be more ‘expressive’ and provide more information. For example, they can allow the driver to judge distance and speed for informed decision making.

To achieve this level of graphics requires considerable memory capacity and a high degree of integration to meet the strict weight and space constraints in vehicles. Cypress Semiconductor has developed the Traveo automotive microcontroller family (Figure 1) for automotive use. Its latest addition is the S6J32xEK series which has a 3D and 2.5D graphics engine and increased on-board memory to support the 3D graphics, up to six traditional gauges, and a heads-up display.

The microcontrollers are scalable with the company’s low pin count HyperBus memory interface. This 12-pin interface operates at Double Data Rate (DDR) and can scale up to 333-MB per sec throughput, enabling it to meet the ‘instant-on’ capability vehicles demand.

Each microcontroller has two HyperBus interfaces to read and write graphical data and other code efficiently. One interface can connect two memories for Firmware Over the Air (FOTA) updates and software fixes, to enhance or add features and applications seamlessly.


Figure 2: Multiple devices can be integrated for graphics, security and low power operation in automotive instrument clusters. (Photo: Cypress Semiconductor)

The microcontroller series uses up to 4-MB of high density embedded flash memory and 512-KB Random Access Memory (RAM) and 2-MB of video RAM (VRAM) which allows the Graphics Processor Unit (GPU) to hold and render more complex images and textures.

There is also an Arm® Cortex® core, operating at 240 MHz and a Low Voltage Differential Signaling (LVDS) video output and a Low Voltage Transistor-Transistor Logic (LVTTL) video output and stepper motor control, which enables the microcontroller to drive two displays.

Support for in-vehicle networking standards for instrument clusters, addresses Controller Area Network-Flexible Data (CAN-FD) and Ethernet Audio Video Bridging (AVB), which provides time synchronized low-latency streaming services to define and connect devices on the network.

For security, in common with other devices in the Traveo family, there is integrated enhanced secure hardware extension (eSHE) support to secure data on in-vehicle networks and to prevent unauthorized connections to ECUs to protect against malicious hacks.

To accompany the high-quality graphics, sound in modern instrument clusters is also a growing requirement. The Traveo S6J32xEK series has 50 channels of 12-bit Analog to Digital Converters (ADCs), 12 channels of multi-function serial interfaces, and I2S interfaces, which are used to connect digital audio devices. There is also an audio Digital to Analog Converter (DAC).

The microcontroller series is sampling now and will be in production in Q1 2018. It is in a 208- and 216-pin Thermally Enhanced Quad Flat Package (TEQFP) and certified for operation in the -40 to +105°C temperature range. Functional safety features support Automotive Safety Integrity Level (ASIL) B.

 Caroline Hayes has been a journalist covering the electronics sector for more than 20 years. She has worked on several European titles, reporting on a variety of industries, including communications, broadcast and automotive.


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