Issues of Automotive system development in the CASE era
Recently, a significant change of development methodology for automotive systems is needed to meet new requirements such as CASE (*1) in the development of next-generation vehicles.
(*1) CASE: Connected, Autonomous, Shared & Services, Electric
Connection to networks and autonomous driving require high performance of communication and sensing, sophisticated coupling between recognition/judgment and control functionality, fulfillment of Functional Safety and security, etc. As a result, automotive systems, especially software, becomes very large-scale and complicated. Moreover, to develop such a complicated system, not only the enhancement of each semiconductor device and software but also the solution of the total system become more important.
The development process for the automotive system consists of three layers; vehicle development, ECU (*2) development and semiconductor (SoC (*3)) development, and each layer collaborates with the others. The enlargement and complication of the system as above make the development period longer in the phase of requirement design for SoC specification in the vehicle and ECU development, corresponding SoC specification design in SoC development, and software design and system verification by using SoC sample. Such long development causes difficulty to apply state-of-arts technology to products immediately. Moreover, when defects are found in system verification and require SoC specification changes, the risk of rework increases to go back more time.
(*2) ECU: Electronic Control Unit
(*3) SoC: System on a Chip
To solve these issues, an SoC vendor is expected to provide a solution to reduce the development period for not only the SoC but also the whole automotive system.
Renesas can contribute to reducing the development period by Shift-left of software development and system verification, which shall enable;
- To establish a methodology to realize parallel and synchronous developments of Vehicle/ECU/SoC.
- To avoid significant rework by verifying complicated use cases in the early phase of development.
Renesas proposes the R-Car Virtual Platform as a key technology for the above.
Objectives of R-Car Virtual Platform (VPF)
Renesas is aiming to realize the following by providing R-Car VPF, a model to emulate the function of the device virtually.
1. Parallel and synchronous development by software development without silicon
Conventionally, a serial development of SoC and software is commonly applied because software is developed by using device samples delivered after SoC development. R-Car VPF enables to start of software development before the completion of SoC development. As a result, parallel and synchronous development using R-Car VPF can reduce the development period of the whole automotive system.
2. No significant rework by system verification in the early phase
Conventionally, because system verification is executed in the latest phase of automotive system development, the overhead of rework is large when defects are found in system verification. R-Car VPF enables Shift-left of system verification before the completion of SoC development. As a result, early system verification using R-Car VPF can reduce the overhead of rework.
Moreover, conventionally, because a serial development of SoC and software is commonly applied, there is the following risk in SoC quality.
- SoC requirements are not fixed in the SoC design phase because software specification is not considered fully before software development.
- SoC cannot be verified with actual software in the SoC verification phase because the software does not exist before software development.
R-Car VPF enables the reduction of the lack of requirements in the SoC design phase and improves SoC quality by use case verification with actual software, by the parallel development of SoC and software. This results in no significant rework to go back to SoC specification design and the reduction of risk to lower specification of the automotive system.
Overview of R-Car Virtual Platform (VPF)
R-Car VPF is a simulation environment to enable software design without a device sample. It emulates the function of the R-Car device on the register interface to enable software design with the same feeling as on a device.
Assumed use case (Expected benefit)
- To start software design before delivery of device sample and migrate to software design on device sample seamlessly.
- To execute system verification, where device and control software operate cooperatively, before delivery of device sample.
- To execute regression test of software both before and after delivery of device sample.
Major features
- R-Car VPF integrates CPU models, and software can be executed on the CPU models.
- Available to read/write access to memory space such as DRAM.
- Address map and calculation accuracy are exactly the same as those of the device.
- Integrated IP models are gradually expanded according to the market requirement.
SoC model integrated into R-Car VPF follows the basic structure of the device. Software is executed on CPU models and control IP models via the Bus model. R-Car VPF and the corresponding device are binary compatible, and it enables the execution of software design seamlessly both on VPF before delivery of the device sample and on the device sample. Each IP model works according to the register write via the Bus model and supports bus master operations such as memory access and interrupt output to CPU models.
R-Car VPF supports the following feature for software design to aim at the same feeling as software design on the device.
- To integrate UART (*4) console as a user interface with software running on the CPU model.
- Some communication interfaces can be connected to resources in the host computer where R-Car VPF is running. Thus, software designers can use the resource in the host computer as the target model of communication.
- To support synchronous connection with various software debuggers for source code debugging.
(*4) UART: Universal Asynchronous Receiver/Transmitter
Development status of R-Car Virtual Platform (VPF)
Renesas Automotive SoC, R-Car series is in mass production of the third generation. For newly-development products after 2021, Renesas is proceeding with the development to provide R-Car VPF.
Renesas has already started to apply the prototype of R-Car VPF to in-company software development. Conventionally, debugging of software is executed on the device after specification design and coding on paper. On the other hand, by starting to debug on R-Car VPF before the delivery of the device sample, software delivery to customers can be accelerated.
In the next step, Renesas will offer R-Car VPF, which can realize software development without silicon, for customers of R-Car to enhance Shift-left of software development and system verification for next-generation vehicles.