Raspberry Pi as a simple thermostat

This folder contains the source files for the demonstration project on using REXYGEN on the Raspberry Pi minicomputer.

In this example the Raspberry Pi is configured to act as a simple thermostat. The temperature is measured by the 1-Wire DS18B20 sensor and the GPIO pin 17 switches a relay on and off with a hysteresis of 0.5°C.

The measured temperature and status of the relay is recorded in the TRND blocks which allow displaying of the trends (graphs) in the REXYGEN Diagnostics diagnostic tool.

Timing of the project

The algorithm runs each 500 milliseconds (0.5 s). See the EXEC function block,
tick x ntick0 = 0.05 x 10 = 0.5

Prerequisites

• REXYGEN Runtime Core, RPiDrv and OwsDrv modules must be installed and running on the target device (Raspberry Pi).
• Owserver (part of the OWFS package) must be installed, correctly configured and running on the Raspberry Pi.
• The DS18B20 temperature sensor must be connected. See the attached wiring diagram.

Running the example

• The *exec.mdl file is the project main file.
• Open it with REXYGEN Studio.
• Specify the 64-bit ROM ID of the attached temperature sensor. See the 1-Wire driver manual below.
• Compile and download it to the target device.
• Switch to Watch mode and observe the algorithm (use Target->Watch Selection to display data).

Documentation

• Press F1 for help on the selected function block in the REXYGEN Studio.
• Getting started with REXYGEN on the Raspberry Pi minicomputer
• RPiDrv - Raspberry Pi driver (including PiFace Digital, UniPi v1.1, Intellisys PIO)
• OwsDrv - 1-Wire driver
• Function blocks of REXYGEN
• REXYGEN Studio User Guide
• Complete documentation of REXYGEN

Additional information

• Raspberry Pi is a trademark of the Raspberry Pi Foundation.
• 1-Wire is a trademark of Maxim Integrated.
• Visit the REXYGEN webpage for more information about the example projects and developing advanced automation and control solutions using REXYGEN.