Embedded Systems Programming: Accessing Databases from Esterel

A current limitation in embedded controller design and programming is the lack of database support in development tools such as Esterel Studio. This article proposes a way of integrating databases and Esterel by providing two application programming interfaces (APIs) which enable the use of relational databases inside Esterel programs. As databases and Esterel programs are often executed on different machines, result sets returned as responses to database queries may be processed either locally and according to Esterel's synchrony hypothesis, or remotely along several of Esterel's execution cycles. These different scenarios are reflected in the design and usage rules of the two APIs presented in this article, which rely on Esterel's facilities for extending the language by external data types, external functions, and procedures, as well as tasks. The APIs' utility is demonstrated by means of a case study modelling an automated warehouse storage system, which is constructed using Lego Mindstorms robotics kits. The robot's controller is programmed in Esterel in a way that takes dynamic ordering information and the warehouse's floor layout into account, both of which are stored in a MySQL database.

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Authors and Affiliations

1. Department of Computer Science, University of York, Heslington, York, YO10 5DD, UK

   David White & Gerald Lüttgen

Corresponding author

Correspondence to Gerald Lüttgen.

Open Access This article is distributed under the terms of the Creative Commons Attribution 2.0 International License (https://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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