ADXpress is a completely new, extremely powerful architecture for data transmission in future vehicles, which has the potential to redefine connectivity within vehicles. This also opens up new possibilities in all aspects of sensor data fusion for ADAS and AD. The number of displays that can be controlled and their maximum resolutions will be significantly increased.

ADXpress is a completely new, extremely powerful architecture for data transmission in future vehicles, which has the potential to redefine connectivity within vehicles. This also opens up new possibilities in all aspects of sensor data fusion for ADAS and AD. The number of displays that can be controlled and their maximum resolutions will be significantly increased. (Bild: Inova Semiconductors)

Whether autonomous driving, growing connectivity or simply more safety and convenience when driving: the use of sensors to capture the vehicle‘s environment and the number of displays to visualize a wide variety of information is constantly increasing, as it becomes an indispensable part of driver assistance systems. This also rapidly increases the data volume in vehicles. Today, it is already around 600GBytes per day. This data has to be transmitted reliably and economically, which today‘s bus systems can only achieve with limitations. With ADXpress, the Automotive Data Express, Inova Semiconductors now presents a solution that enables the transmission of data in the vehicles of tomorrow in a completely new dimension.

Sensors and Displays with different Requirements

Lidar and radar undeniably have a key function in ADAS sensor technology, but numerous camera systems also support the recognition of the vehicle environment in real time. In the course of sensor data fusion, the system then calculates an environment model, which in turn serves as the basis and elementary prerequisite for new, innovative assistance solutions or for autonomous driving itself. However, this sensor fusion also means that many different sensor data must be available with low latency and, above all, synchronously in a time-related context at the evaluation unit or also at several evaluation units simultaneously (e.g. multitasking on several spatially separated computer units).
Intuitive operator interfaces of the driver assistance systems (HMIs, Human Machine Interfaces) for individualizing the car on the road to autonomous driving simultaneously lead to an increasing number of displays in the vehicle. These are constantly getting bigger, have an ever higher resolution and therefore require more and more bandwidth to transmit the image data.

Benchmark DATA

ADXpress Logo
(Bild: Inova Semiconductors)

With ADXpress, all raw sensor data can now be transmitted via, sensor-individual virtual data paths with deterministic latency to one or more evaluation units. The sensors can be connected to an ADXpress node via PCI Express, Ethernet or SPI, whereby the data transfers are currently carried out electrically via a 30Gbit/s link. The data rate is essentially limited by the transmission medium, because the physical layer is already prepared for optical media, allowing data transmission at speeds of 4 x 24Gbit/s.

Requirements for the Topology of the Transmission System

Whereas pure display connections are literally a „bandwidth guzzler“ because pixel data is simply transmitted bit by bit, the topology of connections of this kind is relatively simple. Essentially, these are now unidirectional point-to-point links that send image data between sender and receiver, with low latency requirements, while these continuous data streams have data rates of up to 10 Gbit/s and more. The situation is quite different with sensors and actuators. Even if the bandwidths here are still in the Mbit/s range for the individual sensors, it is the large number of sensors that makes the difference here. A lidar system with five sensors and camera support, for example, already reaches the Gbit/s range. Unlike displays, however, the requirements for the topology of the transmission system are much higher here; in particular, a low latency for a large number of individual data paths with deterministic latency times of the individual paths for synchronizing the data is required here. Five lidar sensors also require five individual connections to the evaluation unit. To arrive at completely new and ever better assistance systems through sensor fusion, this data from the sensors distributed spatially across the vehicle must be able to be captured effectively, but then be available for evaluation elsewhere – usually multiple computers distributed throughout the vehicle.

But even with displays, the demands on the topology of the transmission system continue to increase, so that repeaters and splitters, for example, are already standard today, and the bandwidth can never be high enough anyway. Even though a data rate of 15Gbit/s (500MHz pixel clock @ 30bit color) for the uncompressed transmission of 4K image data (2,160p) is perhaps only to be found in the premium segment, the quantity or number of video links also ensures a high data volume here, as four full HD connections already require 15Gbit/s.

Virtual Data Paths with ADXpress

The ADXpress technology consistently follows the basic idea of combining many different data paths on a serial 30Gbit/s data link – as was already the case with APIX, the Automotive Pixel Link from Inova Semiconductors, which premiered in vehicles in 2008 and is currently on the market in its third generation (APIX3 with 12 Gbit/s) with around 170 million nodes installed worldwide to date.

Unlike APIX, however, ADXpress is a universal mass data transport system that electrically transmits any type of data – whether pixel, Ethernet or sensor data from camera/lidar/radar – via a 30Gbit/s link. The data rate is essentially limited by the transmission medium, because the physical layer is already prepared for optical media, with which 4 x 24Gbit/s can be transmitted.

With ADXpress, this opens up completely new possibilities in terms of network architecture and topologies: among other things, the technology allows new approaches to the implementation of today‘s video interfaces, for example via PCI Express. Figure 1 shows an example of a simplified network.
ADXpress technology is based on virtual data paths, which are realized by transmitting data cells of constant size, with all cells taking the same path through the network. Unlike IP (Internet Protocol), where a packet can reach its destination via a different path than previous and subsequent packets, with ADXpress latency and jitter are constant on a virtual path.
Virtual data paths based on data cells have the great advantage that multiplexing, repeating and duplicating can take place on the layer processing the data cells independently of the service (Figure 2). Particularly with multiplexing, it is possible to control or steer the bandwidth allocation and the latency of the individual data paths. The clever thing about this is that the 128 virtual data paths of the ADXpress only „consume“ bandwidth when user data is actually being transmitted.

Figure 1: This is what the typical network topology of an ADXpress system in a car might look like. The possible interfaces and their spatial distribution within the vehicle are also clearly visible.
Figure 1: This is what the typical network topology of an ADXpress system in a car might look like. The possible interfaces and their spatial distribution within the vehicle are also clearly visible. (Bild: Inova Semiconductors)

ADXpress in Lidar and Radar Systems

Lidar and radar systems often only perform to their full potential when combined with other sensors or camera systems in the context of sensor fusion. In this context, data pre-processing at the sensor is often not useful, as only the joint evaluation of the raw data from all sensors provides a (plausibility checked) picture of the situation. This is necessary, among other things, for 360° radar detection. With ADXpress, all raw sensor data can now be transmitted via, virtual data paths with deterministic latency to one or more evaluation units. The sensors can be connected to an ADXpress node via PCI Express, Ethernet or SPI.

Figure 2: Virtual paths enable user-defined routing of data in each ADXpress chip. This allows data streams to be flexibly fed in or moved out at any node within the network. The individual virtual example data paths are each shown dotted in different colors. A total of 128 different virtual data paths are possible.
Figure 2: Virtual paths enable user-defined routing of data in each ADXpress chip. This allows data streams to be flexibly fed in or moved out at any node within the network. The individual virtual example data paths are each shown dotted in different colors. A total of 128 different virtual data paths are possible. (Bild: Inova Semiconductors)

Packetizing in the Hardware

Generic „application adaptation units“ for burst and stream data implemented in hardware enable „software-free“ packetizing and de-packetizing of continuous (radar, lidar, video) or burst-oriented data (PCI Express, Ethernet, SPI) into a uniform cell format with ADXpress. This makes it possible to packetize burst and stream data with particularly low latency. This, in turn, enables simultaneous bundling of a large number of interfaces across several functional units due to the bidirectional structure of ADXpress – in any direction and with any input and output points.

ADXpress: A universal Network Topology

These features enable universal network topologies that can be adapted to any conceivable interface. Each ADXpress chip implements a gateway function at the application interface and a routing function for the virtual data paths.

Imagine a complex network with several routers, gateways and gateway routers (Fig. 1 and 2), which simultaneously transmits a variety of different data via one or more bidirectional serial interfaces. For example, ADXpress devices can connect SoCs via their PCI Express interface, while simultaneously transporting multiple video streams in any direction via the same serial interface. The ADXpress device functions as a router for the virtual data streams and/or as a gateway to the applications. With its gateway functionality, an ADXpress device offers the possibility of either feeding data into the network (sensors, SoCs) or outputting it (displays, loudspeakers, light, actuators, SoCs). With its router functionality, it distributes data throughout the network via virtual data paths. Figure 3 shows examples of different bandwidth allocations for different applications and architecture configurations.

ADXpress can directly and adequately serve both centralized and decentralized data processing approaches. For example, it is possible to connect satellite control units both centrally to an SoC and simultaneously communicate directly with other satellite control units. With ADXpress, one can rightly speak of a new dimension of connectivity in vehicles, as the familiar point-to-point or point-to-repeater concepts can be replaced by much more integrable and flexible topologies – and all this with deterministic and very low latency.

Flexibility enables Expanding the Transmission System

Expandability for equipment options and model upgrades will be a key requirement for new network architectures in cars to create universal and thus cost-effective platforms. The ADXpress technology makes it possible to design flexible and expandable network topologies and to extend them later at any time or depending on the equipment option. ADXpress makes it possible to reach the entire existing network from one point. Similarly, virtual paths can be freely redirected or cloned, which also enables a wide range of special functions that play a role in, among other things, official vehicles, diagnostic purposes, etc.

Fig. 3: Possible bandwidth distribution in an example ADXpress system in a multi-video application in both directions with 4x Ethernet and GPIOs.
Figure 3: Possible bandwidth distribution in an example ADXpress system in a multi-video application in both directions with 4x Ethernet and GPIOs. (Bild: Inova Semiconductors)

ADXpress provides Bandwidth Scalability

For future applications with ever more and higher bandwidth requirements, scalability must also be as easy to implement as possible. This is in the interest of the OEM and Tier1, as it means they do not have to constantly develop completely new platforms with new semiconductors from scratch. ADXpress therefore offers the option of working with different bandwidths for the physical layer (PHY) – both via electrical and optical transmission media. This not only minimizes development costs and avoids compatibility problems, but it also ensures that ADXpress remains future-proof for a long time, even with very high requirements.

The ADXpress prototyping board
Figure 4: The ADXpress prototyping board will be showed to the public for the very first time at electronica 2022. (Bild: Inova Semiconductors)

Prototyping ADXpress with FPGA

Due to the flexibility in the choice of PHY, the ASIC complete system can also be implemented in modern FPGAs (for example from Achronix or Xilinx). This enables test systems in the FPGA with full access to all ADXpress technology (frame grabbers etc.). Users can already create their prototypes on the target technology, which can then flow seamlessly into a final ASIC design. This saves a lot of time in system development, while allowing developers to detect potential system design errors at an early stage of development. In addition, it is possible to build special solutions based on FPGAs for small series for which an ASIC solution is not cost-effective.

Fig. 5: Possible bandwidth distribution in an example ADXpress system using three PCIe interfaces as well as three Ethernet interfaces.
Figure 5: Possible bandwidth distribution in an example ADXpress system using three PCIe interfaces as well as three Ethernet interfaces. (Bild: Inova Semiconductors)

Comment: ADXpress – the new standard?

The technical article tells you the technical features of ADXpress, but as we all know, it is not only the technology that decides whether an architecture will really become successful. As there are more factors of success it is now time to look at some pieces of background information.

From the very beginning, fabless semiconductor manufacturer Inova Semiconductors, founded in 1999, has been involved in the development of very fast communication devices. The first product, Gigastar, was a universal 1.2Gbit/s device that was first used as a display link in industry. The APIX series was then developed on this basis in 2005, with Inova responsible for development and production while BMW provided the corresponding automotive requirements and inputs. Around 170 million APIX chips are now installed in vehicles, and APIX3 currently transmits data at up to 12Gbit/s. The basic idea behind ADXpress is similar to Ethernet, namely data transmission in the form of small packets, but while Ethernet generates the packets via software, this „packetizing of the data packets“ in ADXpress is carried out extremely quickly via hardware. „Our core know-how is on the one hand serial high-speed data transmission but on the other hand also the knowledge of how to manufacture and test as well as how to bring these products to market,“ emphasizes Roland Neumann, CTO of Inova. „We‘re not just an IP company thinking things up, we are really bringing Gbit-SerDes to the market as a robust, reliable product and we can also bring the functionality to the customer for implementation.“ Although he is clearly the technical mastermind behind the Inova products, Roland Neumann always points out that only the cooperation within the Inova team but also with the foundry, the test facilities etc. and especially with the lead customers made the products possible in the first place.

The CTO himself learned semiconductor design at Siemens in the early 1990s, refined it at Motorola in the „Autobahn“ project, among others, and then, in 1999, he was one of the founding fathers of Inova Semiconductors together with CEO Robert Kraus. For Roland Neumann, it is important „that the chip can also be tested“. He emphasizes that ADXpress was „born out of what we learned from APIX3“. For him, learning here means „designing the system in such a modular way that you can easily expand it“, and this is how, with ADXpress, „a system architecture was created that is so modular that you can expand everything – even the physical layer.“ Neumann highlights „really good customer support“ as a success factor: „We listen extensively to clients because understanding the application is at least as important as the design itself.“

The fact that Inova is a good listener and has a feel for the needs of the market is proven not only by APIX but also by the (history of) Iseled/ILAS technology, which not only solves the binning problem with LEDs but also enables the serial control of many LEDs via a serial, robust and automotive-compatible bus with its special protocol. To this end, CEO Robert Kraus has so far brought together 42 (soon to be 45) very well-known, often directly competing companies from all parts of the supply chain into the Iseled Alliance, thus enabling a complete infrastructure built around the technology. Presumably, Robert Kraus will again work with an alliance for ADXpress to ensure that the high-speed architecture finds its way into customer designs in a short time. Let‘s see what the company announces about this at the electronica show…

Alfred Vollmer, Editor-in-Chief, AUTOMOBIL-ELEKTRONIK

System Definition of ADXpress with SystemC

Inova Semiconductors used SystemC for the entire system development of the ADXpress cell transport system, including the hardware packetizers, SERDES and PHY interface. With this model, the semiconductor manufacturer determined and optimized all essential system parameters such as latency times, bandwidth requirements, buffer sizes, cell sizes, etc. even before the implementation of the logic began.

This simulation model – extended with a GUI – will also be available to ADXpress users. This allows developers to model and simulate customer-specific network architectures very effectively and close to the hardware in order to optimize system parameters, configurations and bandwidth utilization in advance.
ADXpress is not just an ambitious concept: in just a few days, at the electronica trade show in Munich, Inova Semiconductors will present a preliminary system (Hall B4, Booth #301) that demonstrates the performance of ADXpress. (av)

Dipl.-Ing. Roland Neumann, Executive VP Engineering and CTO at Inova Semiconductors in Munich

Dipl.-Ing. Roland Neumann, Executive VP Engineering and CTO at Inova Semiconductors in Munich

Fabian Kluge Inova

M. Sc. Fabian Kluge, Senior System Engineer at Inova Semiconductors in Munich

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