"The embedded system built around the NEC V850/Nucleus PLUS couple turns to be especially fast and reliable. Because of its fast and easy implementation (about 2 days), the Nucleus PLUS real-time kernel allowed us to start rapidly the software development. Moreover, the Nucleus PLUS philosophy is really well adapted to the evolution requirements of the software platform. The availability of the C source code allowed us to easily add services which are vital for our application, as energy management, at the very heart of the real-time kernel".
--Gerard Morin, T2 Project manager, Ascom

Ascom Integrates Nucleus® PLUS in its New Generation of Payphone Systems

Ascom, a swiss group represented internationally with more than 10,000 employees around the world, is specialized in telecommunications and automated services. The Ascom "Payphone and Multimedia" division has gained recognition on the worldwide payphone market, through its expertise of the economical and cultural environment of payphone networks, acquired in more than 25 years through all the continents, and a technological polyvalency which serves an offer including all types of payphones and large families of supervision systems.

Since the beginning of 1999, Ascom has taken a turn to eBusiness, and is providing services, tools and products, means of security and payment, to the companies using transactions on the Internet. Because payphones represent a source of profit for a telephony company, Ascom, as a partner, is committed to profitability objectives. Today, a payphone is supposed to provide not only communications, but also a way for accessing to other services, as consulting bank accounts, reading a health card, refilling an electronic wallet, etc. It should also accept various means of payment, as prepaid telephone cards, credit cards, electronic wallets, coins… Payphones have definitely become complex systems.

It is in this context that the T2 program was launched within the Ascom "Payphones & Multimedia" division. The objective was to realize an intelligent platform allowing to answer the needs of the worldwide market of payphone systems. T2 is a standard technical platform that can be used on any new device, "a set of software or electronics basic bricks, that will be integrated in all our products," said Gerard Morin, T2 project manager. Between 50,000 to 100,000 units per year of the T2 platform should be produced during the next five years.

Totally realized in less than 18 months, the T2 has been designed upon audacious technological choices, allowing to reduce the costs and availability delays. The main criteria associated to this project were to obtain the lowest possible cost price, industrialization and customization costs. The selected architecture, in using twice less components, also allowed to divide in two the total cost price.

In order to achieve this result, two major choices have been realized. "First, at the hardware level, we have chosen a dual processor solution," M. Morin explains. " We are using a RISC processor (the NEC V850) to support the central kernel, the use of plastic money - from the card to the secret treatment -, and the devices -keyboard, etc.-, and a Texas instruments DSP for the telephone signal aspect, including the modem."

In this architecture, all the specifics are software defined, which offers a major advantage : scalability. "On the CPU side, this architecture offers a complete scalability of the payment chain, which is particularly important because of the continuous evolutions of the plastic money word, with the EMV (Europay Mastercard VISA). The DSP, for its part, allows a software management of the modems and signal processing evolutions," M. Morin continues.

On the software side, two important technical choices have also been realized : the building of a software platform around a real-time kernel - Nucleus PLUS -, and the use of a CASE (computer-aided software engineering) - Tau, from Telelogic - for the application part.

The changeability of the T2 software is based on a basic layer named KAWA (Kernel for Advanced and Written once Application), which provides all the main services of a payphone application:

The second characteristics of this software architecture is the application, which sequences all these general services, and manages the specific services, depending on the marketing requirements. It is written in SDL, a formal language characterized by its qualities in terms of productivity and security. The development has been achieved using the tools provided by the Tau complete environment from Telelogic. Consistent and self-contained, this environment has allowed to develop in parallel the application and the KAWA operating platform.

The choice of the Mentor Graphics Nucleus PLUS real-time kernel is the result of an evaluation realized on seven competing products. The criteria which allowed Nucleus PLUS to distinguish itself included:

• The fact that all the low level services were directly linked to the processor;
• Its speed, resulting from its very low consumption operating mode - a payphone system is generally powered only by the telephone line, which doesn't require more than 20 to 50 mA;
• The source code availability, which made it possible to encapsulate the kernel and to modify some aspects of it;
• The possibility to guarantee real-time by fixed tasks priorities;
• The royalty free licensing mode of Nucleus PLUS - very large volume production;
• Finally, the access to protocol stacks (TCP/IP, particularly), and the possibility to design an Internet server.

Entirely developed in 18 months, the T2 software is remarkably compact: the KAWA environment does not represent more than 250 Kb, and the application by itself is less than 200Kb.

Ascom corporate website