Hardware Design

The electronic circuit design was completed first. The earlier consultation and preparation of the subsequent proposal had identified many of the components required by the detailed design. When completed, the electrical design was reviewed with the customer to ensure it met their original criteria. On approval the design was committed to a circuit board. This stage took into account the size and shape of the enclosure to be used for the operator's console, to ensure the two parts would fit together later. Detailed design of the mechanical enclosure, including the safety cover, followed. As each component was finalised it was issued for manufacture, thus minimising delays in the whole project.

Software Design

With all the hardware design complete attention now turned to the software. This software was split into two parts. The first was the embedded control programme for the microcontroller that resides in the test console, the second part was the PC based user interface. Both programmes were written in a high level language, namely C. The two programmes communicate with each other through a RS-232 serial data link.

The Embedded Software

This was designed to respond to simple text commands by performing operations like switching a relay or making a single voltage measurement. This simplicity made both hardware and embedded software testing quick and easy, as all of the equipment's basic functions could be verified as working correctly by using just a dumb terminal. Having established that the test station was fully operational we could now write and test the automatic control program for the host PC.