Raspberry PI Breakout Board for Heating and Ventilation Control
The RaspberryPi has a 26 pin General Purpose Input/Output (GPIO) connector on its top. The usage is indicated in the figure. Note that the connector is not commutation safe, while most connectors have some edge on their housing to prevent commutation the Raspberry has not. So check the sketch, it will be valid also, if you look on top of the pins of your secondary board.
After first attempts with strip boards, I finally descided to do my layout using kicad.
The following break out board may be connected via bus cable to either Raspberry PI version 2 or 3.
- 2 AD-converters to read up to 16 sensors
- onewire connector for DS18B20 remperature sensors
- 5 external relays, controlled via opto couplers, may be operated by externally supplied voltage (5V or 12V)
- 2 PWM outputs to control house ventilation
- conector to control by-pass flap with DC motor
- by-pass motor is operated at 30 V, but the external power supply may be altered easily
- connector for ultra-sonic sensor HC-SR04 to monitor water reservoir
- RS232 may be connected alternatively to ultra-sonic sensor, if R24 = 0 Ohm and R25 open.