Graphical system design and simulation lean toward the expensive realm of high-end tools like the MathWorks' Matlab or Unified Model Language (UML) products. Test tends to be overkill for small embedded projects. Thus, Cypress Semiconductor created the PSoC Express tool specifically for its 8051-based, mixed-signal PSoC microcontroller.
PSoC Express is very manageable and easy to learn, given the limitations of the target processor. The PSoC chip contains a collection of analog and digital building blocks around a processor and memory core. Developers can create custom logic PSoC Designer, but this takes a good bit of expertise. Likewise, application code needs to be written to take advantage of this custom configuration.
PSoC Express takes a higher-level approach by using a set of standard peripherals that can be mapped onto the building blocks (see the figure). Designers pick and place these standard peripherals, such as ADCs, DACs, switches, and digital I/O, onto a graphical workspace. Then the peripherals can be linked together using a simple table-driven interface. Buttons can be joined to controls or LEDs.
Analog inputs can generate digital outputs. The combinations are up to the designer, and the code is automatically generated. System simulation can be interactive or database-driven, so that systems can be tested without hardware. Simple control systems can be designed in PSoC Express alone in a few minutes.
PSoC Express is downloadable from Cypress' Web site: www.cypress.com.