SITE MAP  CONTACT US

Volume 23 (Sep 08, 2004)

The Challenges and Passion Behind the Creation of the V850 Series (1/2)

Part 2: The 32-bit RISC single-chip microcontroller-Taking on the challenge of the automotive field

The challenge begins for the automotive field.

The V850 Series-a 32-bit RISC single-chip microcontroller with the world's highest performance-survived numerous obstacles and was announced in a press release in August 1994. This announcement would bring with it an opportunity to further accelerate the movement toward the development of high-performance microcontrollers. Within the company, discussions regarding what types of applications could be employed to make the best use of 32-bit RISC microcontrollers began to intensify. It was then that the engineers began examining the possibility of creating high-end applications that could be used in the automotive field. The initial targets were engine and high-end chassis control systems.

In 1994, the majority of microcontrollers employed for engine and chassis control systems were 16-bit CISC microcontrollers. Despite growing understanding of the 32-bit microcontroller's high level of performance, there were still concerns about the longer program code, larger chip size, greater power consumption and more. Many believed that the 16-bit microcontroller era would continue for the time being.

It was true that 16-bit microcontrollers might be sufficient if control systems were to be continued in the same conventional manner. However, in attempting to keep exhaust emissions below regulation levels under every possible condition, while at the same time improving fuel consumption and eliciting higher performance, the design team realized that the performance of 16-bit microcontrollers would no longer suffice. In addition, with concern over environmental issues and safety increasing, automobile manufacturers were looking to make improvements in every aspect of performance. To control a large volume of software within a fixed period of time, the simultaneous development of a new engine and a high-performance microcontroller would be necessary.

Although NEC (at that time) was experienced in employing 16-bit CISC microcontrollers for engine and chassis control systems, there were still a number of issues to be dealt with, including the fact that the company did not have a complete product line-up. Therefore, NEC was not well known as a supplier of microcontrollers for automobiles in the field of high-end control systems.

Shoji Matsubara (manager, Automotive Systems Division) comments, "32-bit RISC and C language were indispensable in creating a new design for the automotive field. I felt this was a chance to make a new start in a completely new environment." This was to be the beginning of a formidable challenge for the V850 Series 32-bit RISC microcontroller in the automotive field.

Creating a new theme: Just how fast could new products be developed?

Matsubara and the other team members immediately began paying visits to automobile and autoparts makers in Japan, the United States and Germany. The team was conducting these promotional activities to bring the performance advantages of 32-bit RISC microcontrollers to the forefront. As a result, customers from several companies voiced interest in the 32-bit RISC microcontroller and NEC commenced actual product development activities in 1995.

The team wanted to respond to customers who had told them they would design with these microcontrollers if they could be developed quickly. However, since engine control is an important element at the heart of the automobile, these microcontrollers needed to have both high reliability and quality. Moreover, because 32-bit RISC microcontrollers had never before been installed in automobiles, development would have to be started completely from scratch. Furthermore, to shorten development time and improve the design flow, there were many problems to be dealt with, such as carrying out mass production by employing flash memory for on-chip program memory rather than mask ROM, and gaining the customers' trust regarding plans to adopt the use of C language. The team worked together to solve these problems one by one.

For example, C language was necessary for the efficient development of software exceeding 100 KB, and high reliability was required for the C compiler. Accordingly, the team made repeated modifications after taking into consideration case examples of defects that had actually occurred in the past.

Since the team had already embarked on the development of an evaluation environment for evaluation chips and peripheral I/O early on, Matsubara was confident that something would work out. In March 1996, a software development tool-albeit tentative-was presented to customers. Then, at the end of 1996, a chip sample for pre-development was completed. However, even though they had succeeded in producing a sample, team members were still far from their ultimate goal and numerous problems remained. They were about to venture down a rocky road.

Between despair and enthusiasm-The greatest challenge: 0.35µm on-chip flash memory

In March 1996, NEC unveiled the V853 microcontroller (Diagram 1), the world's first 32-bit RISC microcontroller equipped with flash memory. This placed the company at the forefront of development of microcontrollers equipped with flash memory. At the time, the 0.65µm process was the mainstream for flash memory. The V853, however, employed a 0.5µm process and received high acclaim as a cutting-edge multimedia RISC microcontroller.

Amidst this situation, Matsubara and the other team members decided to implement a 0.35µm process to realize on-chip memory with high capacity and high performance, as well as to make it compatible with the long life of automobiles. Although the designers were already experienced in developing a microcontroller equipped with flash memory, as exemplified by the V853, this was the first time they attempted to develop one using a 0.35µm process. Wanting to respond to customers who had said, "We know NEC enjoys challenges and our expectations are high," Matsubara swore in his heart that he would do his best. However, since the product was to be developed on the premise that it would actually be used in the in-vehicle field, the vehicle environment in which it would be used had to be thoroughly considered and the team had no choice but to repeatedly carry out trial productions and evaluations.

The team seemed to be having a difficult time creating a sample that met its objectives. There were even times when some members felt that if they didn't finish the sample they were working on before the set deadline, they would not be able to continue. Kazumi Fujito (senior product technology professional, NEC Kyushu, 2nd Production Engineering Department), who was in charge of production, says about the troubles faced during trial production, "Honestly, I didn't think we were going to be able to pull it off." However, there was nothing they could do but seek the best possible production conditions. Fujito states with deep emotion, "After carrying out trial production after trial production, we were finally able to determine the optimum conditions for production."

There were countless occasions on which the engineers wanted to make excuses for why they were unable to produce a sample. It was during those times that Matsubara found himself personally telling the others, "There is no room for excuses." This was because making excuses would mean that they were in effect backing down from carrying on this development. For more than half a year, the team members found themselves going home on the last train on a daily basis. During this time, they went back and forth between moments of despair and enthusiasm. Yet, in the end, they always arrived at the conclusion that they must carry on.

| 1   2 |

AdvancedParametric