Arduino-Based Automated Control and Multi-Sensor Data Acquisition System for Coffee Grinder

Abstract

Post-roast coffee processing and quality evaluation require consistent mechanical grinding and reliable acquisition of physical bean characteristics. This study presents the design and implementation of an automated control and multi-sensor data acquisition system for a coffee grinder based on the Arduino Uno microcontroller. The electromechanical subsystem automates a 220 VAC electric motor using an active-low optocoupled relay connected to digital pin D13, operating under a precise 45-second timed grinding cycle. The integrated testing chamber incorporates a stabilized four-point LED illumination array governed via digital pin D5 through a 220 Ω current-limiting resistor to ensure consistent measurement conditions. Physical characteristic acquisition combines a TCS34725 digital color sensor operating over an I2C communication bus (pins A4 and A5) and a metal-oxide semiconductor gas sensor array (TGS2602, TGS2620, and MQ-135) interfaced with 10-bit analog-to-digital converter channels (pins A0, A1, and A2). The custom power distribution circuit steps down 12 VDC input into two isolated +5 VDC rails using dual LM7805 linear regulators with diode 1N5408 reverse-polarity protection and a 5×20 mm fuse, effectively isolating microcontroller logic from actuator inrush noise. Experimental test-point measurements confirmed supply rail stability at 4.97 V and idle I2C bus levels at 4.94 V (SDA) and 4.96 V (SCL). Baseline gas sensor characterization under ambient clean air yielded stable median voltages of 1.698 V (TGS2602), 1.058 V (MQ-135), and 0.210 V (TGS2620). Sensor telemetry is structured and streamed via UART serial communication at 500 ms intervals without packet loss. The developed platform demonstrates robust electromechanical sequencing and synchronized multi-sensor telemetry, establishing an objective hardware foundation for post-grind coffee evaluation.