DENSO Corporation is a leading supplier of advanced automotive technology, systems and components for automotive manufacturers worldwide.


The key factors of choosing IAR Embedded Workbench are performance and functional safety certification. We think tool performance affects the return on investment of our product. For example, when we get 20 percent faster code than before and the code size advantage compared to previously used tools are huge, it will create 20 percent of resource for considering additional value. Obviously smaller code size requires smaller memory budget MCU, which will reduce overall MCU component cost. Finally, the tools from IAR Systems are able to deliver reduced cost for our end customers.

- DENSO engineer

DENSO Corporation is a leading supplier of advanced automotive technology, systems and components for automotive manufacturers worldwide.

We interviewed a team of engineers in the Engineering planning department of basic software engineering group at DENSO. This department is responsible for compiler evaluation, tool selection and quality assurance work for tool standardization within DENSO.

DENSO is using IAR Embedded Workbench mainly for several small motor control applications based on 16-bit MCUs, and the use case is increasing for body, chassis, intelligent sensor and engine control of power train applications. In addition to the standard edition of IAR Embedded Workbench for RL78, DENSO is also using the functional safety edition of the toolchain.

Selecting a toolchain

First of all, DENSO did not have a reference compiler for use with 16-bit MCUs but they had for 32-bit MCUs. However, a demand of 16-bit MCUs has been increasing because of intelligent mechanical components/sensor control and small motor control use case promotions. Compiler standardization of 16-bit MCUs was difficult due to a historical reason, as development tools for 16-bit MCUs have been tied up with each MCU architecture during a history of mergers and acquisitions in the semiconductor market. Especially for Renesas 16-bit MCU product line up merger into RL78 family, choosing a reference compiler was a relevant action for DENSO.DENSOWAVE with Product_ver1.jpg

As you know, there are many choices of compilers offered from semiconductors, third-parties or open source vendors. We needed to select the best one for our end customers who are the automotive manufacturers. We evaluated toolchain performance and quality benchmarks, licensing options, return on investment, and technical support agreement. After the evaluation, we chose to go with IAR Embedded Workbench.

- DENSO engineer

IAR Systems’ tools differ from other companies’ tools due to the 16-bit MCUs support and a variety of development kits including board support package. Our impression is that most tool companies want to get into high-end market competition, so there are very few tool companies which provide a rich portfolio for low-end MCUs. We are hoping IAR Systems will continue to support low-end MCUs and in our case making it possible to use IAR Embedded Workbench for applications such as sensor control in automotive products.

- DENSO engineer

IAR Embedded Workbench provides a complete toolchain. For DENSO, the simulation environment is also an important component of the toolchain.

The software simulation environment in IAR Embedded Workbench is available from start. We know several tools which do not provide simulator environment. For us, the simulator is mandatory not only for software component standalone evaluation but also for compiler evaluation.

- DENSO engineer

High-performance compiler

During the research for a new toolchain, DENSO performed both industry benchmarks and their own testing. DENSO’s own testing reported that the code speed of the compiler in IAR Embedded Workbench was, on average, 20 percent faster than Renesas own compiler and 30 percent faster in most cases. (The benchmark result does not promise today’s performance differences.) In addition, the code size was 20 percent smaller even with moderate optimizations settings. DENSO concluded that IAR Embedded Workbench provided a good balance between code speed and code size. A deep dive analysis also showed that IAR Embedded Workbench required less instruction because of a good implementation of the Renesas ABI (Application Binary Interface).

Choosing a pre-certified toolchain for functional safety

DENSO is working with several different automotive manufactures and they have different needs in the level of functional safety. To meet their requirements, DENSO decided to go with a pre-certified toolchain from IAR Systems.

We need to pay all necessary cost and engineering resources to pass a certification process, if the applied compiler is an uncertified tool. If it is the case, the cost for making the certification is much higher than purchasing a pre-certified compiler tool. Basically, there are two types of functional safety tool solutions from tool suppliers. One solution is to provide a pre-certified tool and another is to provide assistance only during the certification process.

- DENSO engineer

From our point of view, the most important compiler features are fast code and the possibility of reusing code. IAR Systems’ tools met with these requirements, so we purchased IAR Embedded Workbench for RL78. Then, as soon as IAR Systems released the functional safety edition of the toolchain, we chose to go with that one as well.

- DENSO engineer

We decided to purchase a pre-certified tool due to difficult work by doing a certification process among non-expert members. For instance, a timeframe of several months is assumed for the process. In addition to that, a certification process needs a compiler expert and business person to communicate or negotiate with the certification authority. Those facts mean that the work is very hard to accomplish.

- DENSO engineer

Flexible licensing, product longevity and local technical support add additional customer value

Other than the performance of the compiler, DENSO considered the following important reasons to choose tools from IAR Systems:

  • IAR Systems offers flexible licensing and pricing options for effective purchasing, as well as Support and Upgrade Agreement process.
  • Product longevity. Product lifecycle in automotive market is very long, usually more than 10 to 20 years. In order to secure such a long supply term, it is important to choose a component or a tool supplier who is committed to this business continuity.
  • IAR Systems offers local technical support through the office in Tokyo. Many companies with headquarters outside Japan only have small sales offices without any local technical support.
  • User support satisfaction. Timely response from IAR Systems Japan office is very helpful to the DENSO engineering team. In addition to that, IAR Systems offers local content-rich seminars which have increased DENSO’s satisfaction level of IAR Systems.

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