Field Study: Use of the Car Communication Analyzer during Development of the CeCaS Standard Platform Architecture for Software-Defined Vehicles

We present the ViGEM Car Communication Analyzer (CCA), a powerful tool for the development of future automotive architectures aka the Software Defined Vehicle (SDV), in the context of the CeCaS Project1. We use the CCA to validate the safety-critical in-vehicle connectivity between sensor specific interfaces, a so-called Zonal ECU, and a centralized computer (see Figure 1 below) with measurements of Key Performance Indicators (KPI) to reach our Quality of Service (QoS) goals.

To allow transition of safety critical data, CeCaS participant partner Missing Link Electronics (MLE) implemented a deterministic networking stack at multi-Gigabit speeds (i.e. TCP/IPv4 over TSN over 25 Gig Ethernet) and employs proven automotive communication middleware that decouples vehicle functions (ADAS) from sensor data interfaces. 

The CeCaS Zonal ECUs implement vital features of the standard CeCaS SDV architecture: 
● First, the CeCaS Zonal ECU physically connects to the sensors (here the cameras via Ethernet and also optional CAN connections ) and has low-latency when processing camera events. 
● Second, the CeCaS Zonal ECU is part of the vehicle backbone running MLE Auto/TSN (i.e. TCP or UDP over IPv4 over TSN over 25 Gig Ethernet). 
● Third, the CeCaS Zonal ECU runs the automotive middleware stack to “terminate” the camera sensor signals and offer camera data under the Publisher/Subscriber concept from above. 

Zonal ECUs are all about connecting many different automotive sensors and actuators, here we used the 25G Ethernet connection for upstream communications analysis.
Figure 4 shows a block diagram of one instantiation of the CeCaS Zonal ECU. It follows the concept of SDV: “Terminating” sensor signals (MIPI CSI cameras, for example) on the left hand Ports side, then entering the PL (Programmable Logic) and then the PS (an ARM A72-based Processing System). The Cariad universal automotive Communication Middleware FLAME is executed on the Linux partition of the zonal ECU. 

When the deterministic, low-latency transport Auto/TSN needed to get validated the ViGEM CCA served as a valuable tool. Based on real-time recording of precision time synchronization and time stamps, KPIs Latency & Jitter could be verified, and we saw proof that the camera data “ages” very little during transport from the camera sensor over the Zonal ECU to the HPC.

Among the many aspects demonstrated and validated with the ViGEM Car Communication Analyzer is the deterministic, low-latency transport when using Auto/TSN. Based on precision time synchronization and time stamps, and thanks to the ViGEM CCA recordings we validated our assumptions and found transmission errors that could be fixed during setup of zonal gateway.

The CeCaS project provided a testbed to quickly build a zonal vehicle architecture demonstrator, in particular, the Auto/RPS HW Zonal ECU component and the Cariad universal automotive Communication Middleware FLAME were crucial for successful rapid prototyping, from providing a vehicle abstraction with a signal to data gateway for legacy vehicle CAN busses, up to the integration of a communication middleware stack for IP-based connections between the zonal ECU and the CeCaS central compute platform (HPC) via TSN over 25 Gig Ethernet. The ViGEM Car Communications Analyzer measurements proved that the initial design assumptions worked out in reality and saved us many hours debugging and error analysis. Its measurements of KPI assured us that our SDV architecture can serve as an industry standard for the years to come.