This library implements RIMS controls for home brewers. For a definition of a RIMS, see What is a RIMS?.

For me, an Arduino microcontroller combined with an LCD Keypad shield was cheaper and far more customizable than a commercial PID controller. With this library, a commercial PID controller is unnecessary. It includes an automatic PID tuning toolkit. Temperature can be read with a thermistor, a resistance temperature detector (RTD), or any custom temperature probe. The heater is controlled via pulse-width modulation (PWM) of a solid-state relay (SSR).

rims-arduino-library Web Site GNU General Public License version 3.0 (GPLv3)

Technical Implementation: FSM and Logic

The project is a sophisticated exploration of software engineering and high-performance embedded systems. It uses a specialized Finite State Machine (FSM) framework to structure code for complex, multi-state projects with robust software logic.

• Software Architecture layer: The RIMS (Recursive Implementation of State-machines) library provides a formal way to define "states" (e.g., IDLE, RUNNING, ERROR) and the "transitions" between them based on sensor inputs.
• Timing Logic layer: Using the millis() function, the library manages time-based transitions without blocking the main execution loop.
• Input layer: Multiple pushbutton switches act as state triggers, moving the system between various programmed behaviors.
• Display layer: The LCD provides a clear and versatile way to show the "current state" and relevant telemetry data in real-time.

Hardware Infrastructure

• Arduino Uno: The primary host for the RIMS library and all associated FSM logic and state-transitions.
• LCD Keypad Shield (or similar): Provides the user interface, display, and input controls. The images below show the various interface screens.
• Solid-State Relay (SSR): Controls the heating element via PWM.
• Temperature Sensor: Can be a thermistor, RTD, or custom probe.
• Hall Effect Flow Sensor: Monitors liquid flow for safety.
• External Speaker: For audible alarms.
• Jumper Wires & Power Supply: For connecting all components.

Features & User Interface

• User interface made with DFRobot LCD Keypad Shield for Arduino or similar (can be customized)
• Heater action: solid-state relay (SSR) time proportioning control (or pulse width modulation, PWM), LED duty-cycle indicator
• Temperature sensor: RTD reading with an instrument amplifier and cubic fitting, thermistor reading with voltage divider, custom temperature probe support, measurement pre-filtering before PID
• PID temperature regulation enhanced: derivative filter, smart integration clamping anti-windup, multiple controller (up to 4, optional) for different mash water quantities
• Automatic PID tuning: Autotuner based on relay identification, Fourier analysis and Ziegler-Nichols methods
• Manual PID tuning: Process model identification tools
• Tripped breaker detection on heater: any 5V DC power-supply
• Countdown timer that is activated only when temperature setpoint is reached
• Data logger: simple serial communication (usb port), SPI flash memory (Winbond 1 Mbytes), USB Menu to access brew data on SPI flash memory (by holding <OK> at startup)
• Hall effect flow sensor: turn off heater if flow is critically low,
• Alarm with external speaker: bad flow\disconnected temperature probe errors, timer is elapsed, no voltage on heater, different frequencies for each alarms (alarm distinction)

Future Expansion

• OLED Identity Dashboard Integration: Add a small OLED display to show a larger life bar and a real-time "State Map" diagram.
• Multi-Sensor Bio-Security Integration Support: Connect several sensors (e.g., ultrasonic or IR) to trigger autonomous state transitions without user input.
• Cloud Interface Registration Synchronization: Add a WiFi module (ESP8266/ESP32) and link to a cloud dashboard to precisely control and track your state data from your smartphone.
• Advanced Velocity Profile Customization Support: Add a small slider or potentiometer to manually adjust the "Timing Thresholds" inside each state transition.

RIMS Arduino Library is a perfect project for any software enthusiast looking for a more interactive and engaging structured-coding tool!

Project Link: https://sourceforge.net/projects/rims-arduino-library/