Hardware/Software Co-Design and Co-Validation Using the SCR Method

Abstract : To date, the SCR (Software Cost Reduction) method has been used to specify system requirements. This paper extends the SCR method to hardware/software co-design and co-validation. Our approach consists of three steps. First, the SCR method is used to specify the required system behavior, i.e., the required relation between environmental quantities (called monitored quantities) that the system monitors and environmental quantities (called controlled quantities) that the system controls. Next, the system designers specify the I/O devices required to compute estimates of the monitored quantities and to set values of the controlled quantities. Finally, the required software behavior is specified as three modules: a device-independent module, specifying how the (estimated) monitored quantities are to be used to compute estimates of the controlled quantities, and two device-dependent modules: an input device interface module, specifying how data from the input devices are to be used to compute estimates of the monitored quantities, and an output device interface module, specifying how the values of controlled variables are written to output devices. To illustrate the approach, we use SCR to specify a simple light control system.