rpi_relay_controller

Relay control program for Raspberry Pi computers written in Rust that only activates relay if weather condition allows operation.

To get weather info the program uses separate program to serve weather info and when the relay control program is started current weather info is loaded from a path defined in a configuration file.

Requirements

• rpi_bme280_server for getting weather info from
• RPPAL compatible operating system and hardware

Configuration

Configuration is loaded from a TOML file that contains parameters required for the operation. Sample of the configuration

Path to the rpi_bme280_server, pin the relay is connected to, operation duration, too low temperature limit and too high humidity limit can be customized to requirements without having to recompile the code and to allow one program to control multiple relays.

Startup using systemd

Samples folder contains following files related to systemd startup:

• sample.service That must be modified to match compiled programs location
  • ExecStart Defines the program that is to be run. Sample assumes that binary is located in /home/Pi/Programs/rpi_relay_controller/ directory and named rpi_relay_controller and that config.toml file is present in the working directory.
  • WorkingDirectory Sets the working directory for the program, if ExecStart line does not contain the configuration file location config.toml file must exist in the working directory.
• sample.timer That must be modified to match required activation interval
  • OnCalendar Defines when the relay should activate, default is daily at 21:00 for more info for the format see systemd.time(7)

Both files can be copied to target systems /etc/systemd/system/ folder with appropriate names for the device the relay controls. After both files have been copied the relay can be started by using $sudo systemctl start sample.timer command.