Issues of Automotive system development in CASE era
Recently, a significant change of development methodology for Automotive system is needed to meet new requirements such as CASE(*1) in 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 / judgement and control functionality, fulfillment of Functional Safety and security, etc. As a result, Automotive system, especially software, becomes very large-scale and complicated. Moreover, to develop such complicated system, not only enhancement of each semiconductor device and software but also solution of total system become more important.
Development process for Automotive system consists of three layers; vehicle development, ECU(*2) development, semiconductor (SoC(*3)) development, and each layer collaborates with each other. The enlargement and complication of system as above make development period longer in phase of Requirement design for SoC specification in 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, a SoC vendor is expected to provide solution to reduce development period for not only SoC but also whole Automotive system.
Renesas can contribute to reduce development period by Shift-left of Software development and System verification, which shall enable;
- To establish methodology to realize parallel and synchronous developments of Vehicle / ECU / SoC.
- To avoid significant rework by verifying complicated use case in early phase of development.
Renesas proposes R-Car Virtual Platform as a key technology for above.
Objectives of R-Car Virtual Platform (VPF)
Renesas is aiming to realize followings by providing R-Car VPF, a model to emulate function of 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 sample delivered after SoC development. R-Car VPF enables to start Software development before the completion of SoC development. As a result, parallel and synchronous development by using R-Car VPF can reduce development period of whole Automotive system.
2. No significant rework by System verification in early phase
Conventionally, because System verification is executed in the latest phase of Automotive system development, overhead of rework is large when defects are found in System verification. R-Car VPF enables Shift-left of System verification to before the completion of SoC development. As a result, early System verification by using R-Car VPF can reduce 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 SoC design phase because software specification is not considered fully before Software development.
- SoC cannot be verified with actual software in SoC verification phase because software does not exist before Software development.
R-Car VPF enables to reduce the lack of requirements in SoC design phase and improve SoC quality by use case verification with actual software, by 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 Automotive system.
Overview of R-Car Virtual Platform (VPF)
R-Car VPF is simulation environment to enable Software design without device sample. It emulates function of R-Car device on register interface to enable Software design in 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.
- 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 device.
- Integrated IP models are gradually expanded according to the market requirement.
SoC model integrated in R-Car VPF follows the basic structure of device. Software is executed on CPU models and control IP models via Bus model. R-Car VPF and the corresponding device are binary compatible, and it enables to execute Software design seamlessly both on VPF before delivery of device sample and on device sample. Each IP model works according to register write via Bus model and supports bus master operation 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 device.
- To integrate UART(*4) console as user interface with software running on CPU model.
- Some communication interfaces can be connected to resource in Host computer where R-Car VPF is runnung. Thus, software designers can use the resource in Host computer as target model of communication.
- To support synchronous connection with various software debuggers for source code debug.
(*4) UART : Universal Asynchronous Receiver/Transmitter
Development status of R-Car Virtual Platform (VPF)
Renesas Automotive SoC, R-Car series are 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, debug of software is executed on device after specification design and coding on paper. On the other hand, by starting debug on R-Car VPF before delivery of 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.