Wiznet makers

A massive 5HP motor roars to life, and the pump head temperature spikes to hundreds of degrees. All of this happens inside a thick, metal sound-attenuating cabinet known as the 'TARDIS'.

This is the home of the air compressor—the heart of any workshop's pneumatic tools—but it is also a graveyard for wireless IoT devices. Extreme heat, intense vibration, powerful electromagnetic interference (EMI), and a metal enclosure that blocks RF signals make it a nightmare for connectivity.

In a project shared by AaronCake from the Home Assistant community titled "Monitoring the Air Compressor in my TARDIS," we see a brilliant example of retrofitting. By combining W5500 Ethernet with robust industrial sensors, he built a monitoring system that survives where others fail.

1. The Connectivity Core: Why W5500 over Wi-Fi?

The most critical design choice was the controller. Unlike typical DIY projects that rely on ESP32 or Wi-Fi modules, this project utilizes the Keyestudio W5500 Ethernet Development Board.

The reasoning is sound. The operation of a large compressor generates significant EMI, and the metal cabinet acts as a Faraday cage, blocking wireless signals. In this unstable environment, the W5500 chip provides a hardwired TCP/IP connection that is immune to RF noise. It offloads network processing from the main MCU (ATmega328P), ensuring stable MQTT message transmission without consuming valuable system resources.

2. Eyes and Ears of the System: Component Breakdown

To go beyond simple ON/OFF monitoring and achieve precise diagnostics, the component selection serves as an excellent engineering case study.

① Enduring 400°C Heat: MAX6675 & DS18B20

The pump head can reach nearly 400°C during operation—temperatures that would melt standard semiconductor sensors.

• MAX6675 & K-Type Thermocouple: The creator used an industrial K-Type Thermocouple paired with a MAX6675 converter (SPI interface) to safely digitize and monitor these extreme temperatures in real-time.

• DS18B20: For the water-cooled chiller, DS18B20 waterproof sensors monitor the water and air outlet temperatures. Their 1-Wire protocol allows for stable signal transmission over long cable runs.
• DHT22: A standard DHT22 handles the ambient temperature and humidity inside the cabinet to control ventilation fans.

② Detecting Mechanical Anomalies: IR Reflectors & Pressure Transducers

What if the motor is spinning, but the belt slips and the pump doesn't turn? Monitoring power consumption alone won't detect this.

• IR Reflection Sensors: By placing reflective aluminum tape on the motor and pump pulleys, IR sensors detect the reflections. The MCU uses interrupt pins to count these pulses, calculating RPM to instantly identify belt slippage or motor inefficiency.

• Analog Pressure Transducers: Tank and regulator pressures are monitored using industrial sensors outputting 0.5V–4.5V. Noise handling is key here: the creator used twisted pair cabling and capacitor filters to ensure the analog signals remained clean despite the noisy electrical environment.

③ Clean Power: PoE Splitter

Complex power wiring invites noise and maintenance headaches. This system uses a PoE (Power over Ethernet) Splitter to deliver both data and power via a single Ethernet cable. This eliminates the need for a high-voltage AC adapter inside the cabinet, creating a safer, low-voltage environment.

3. Beyond ON/OFF: True Diagnostics

This system doesn't just check if the machine is running; it analyzes the equipment's health like a doctor diagnosing a patient.

• Mechanical Health (RPM Monitoring): By measuring Motor RPM vs. Pump RPM, the system can detect mechanical failures. If the motor spins but the pump doesn't, it indicates a broken or slipping belt.
• Thermal Management: With precise readings from the thermocouple and DS18B20s, the system prevents overheating damage by monitoring the 400°C pump head and the cooling efficiency of the chiller.
• Pressure Balance: Simultaneous monitoring of tank and regulator pressure ensures the air supply meets the required specifications without fluctuation.

4. Destination Data: Integration with Home Assistant

Hardware collects the data, but software gives it value. This project completes the loop using Home Assistant, an open-source home automation platform.

• Lightweight Communication (MQTT): The Arduino transmits temperature, pressure, and RPM data via MQTT, a lightweight messaging protocol. Thanks to the W5500's stable Ethernet connection, data streams in real-time without packet loss.
• Dashboard Visualization: The Home Assistant Lovelace UI visualizes this data with gauges and graphs. The user can check the internal status of the "TARDIS" from a smartphone without ever opening the noisy cabinet.
• Smart Automation:
  • Alerts: Instant notifications if the pump head temperature exceeds critical safety limits.
  • Control: Logic to keep exhaust fans running after the compressor stops until the internal temperature drops to a safe level.

5. Why This Project Matters

This project is a definitive example of "Brownfield Monitoring"—transforming legacy equipment into smart devices without replacing them.

It demonstrates that for industrial environments or high-noise areas, the instability of Wi-Fi can be effectively solved using WIZnet’s W5500 chip for wired connectivity.

"Transmitting data quietly and accurately from the noisiest place in the shop."

It proves that the "Right Technology"—in this case, robust wired Ethernet and industrial sensors—is far superior to chasing the latest wireless trends when reliability is paramount.

❓ FAQ: 5 Questions Engineers Might Ask

Q1. Why use wired Ethernet (W5500) instead of the more convenient Wi-Fi (ESP32)?

A. Two decisive factors: RF Shielding and EMI. The compressor sits inside a metal cabinet that acts as a Faraday cage, blocking Wi-Fi. Additionally, the massive inrush current and operation of the motor generate electromagnetic interference that can cause Wi-Fi connections to drop. For reliability in industrial settings, isolated wired Ethernet is the gold standard.

Q2. Is it safe to measure 400°C with an Arduino?

A. Standard silicon sensors (like LM35 or DHT22) will fail above 150°C. This project uses a K-Type Thermocouple, which uses the voltage difference between two dissimilar metals to measure heat, combined with a MAX6675 digital converter. This allows the low-voltage Arduino to safely read extreme temperatures.

Q3. How is RPM measured accurately?

A. It uses a non-contact optical method. Reflective tape is applied to the pulleys, and an IR sensor detects the light reflected as it passes. The MCU captures these pulses via Interrupt pins to count the revolutions precisely, ensuring no data is missed even at high speeds.

Q4. Can low-voltage sensors coexist with 220V power lines?

A. Ideally, they should be physically separated. This system uses a PoE Splitter to bring in 12V/5V DC power via the Ethernet cable. This avoids running additional 220V AC lines for the monitoring system inside the cabinet, significantly improving safety and reducing noise.

Q5. If I were to build this today, is there a better hardware option?

A. While the original used an Arduino Uno clone, today we recommend the W5100S-EVB-Pico or W5500-EVB-Pico. These are based on the Raspberry Pi Pico (RP2040), offering much higher performance. They also support MicroPython or CircuitPython, making it far easier to implement MQTT and sensor logic compared to C++.