ProtoCentral easyISO — Isolated Qwiic Adapter

The ProtoCentral easyISO galvanically isolates a Qwiic / STEMMA QT I²C link — both data and power — so a sensor wired to your body does not share a ground with a mains-powered laptop or bench PC. Plug your host into one side and your sensor into the other. Nothing else changes: the same library and the same I²C address, with an isolation barrier in between.

Why it matters: a laptop running on its charger couples mains-frequency leakage current onto its USB ground. With electrodes on the skin, that current flows through the body and shows up as 50/60 Hz hum, baseline wander or a saturated front end. Running the host from battery avoids it, and easyISO lets you stay plugged in.

How it works: a TI ISO1640 hot-swappable I²C isolator carries SDA and SCL bidirectionally across a silicon-dioxide capacitive barrier at up to 1.7 MHz. An MPS MIE1W0505BGLVH isolated DC-DC module powers the sensor side, so no wire crosses the barrier. Each side has its own 10 kΩ I²C pull-ups and decoupling.

Getting started: connect a Qwiic cable from your Arduino, ESP32 or Raspberry Pi to the host port and your sensor to the isolated port. Run your usual sketch. The adapter is transparent to software. Every Qwiic / STEMMA QT sensor works through it, from ProtoCentral or any other maker, including our tinyGSR v3, as long as the sensors on the isolated side stay within its 3.3 V, ~75 mA supply. Prefer a breadboard? Each side also has a 0.1″ SCL / SDA / VCC / GND header.

Features

• Isolated I²C and isolated power in one adapter — no separate supply needed on the sensor side
• TI ISO1640 bidirectional I²C isolator: hot-swappable, up to 1.7 MHz, clock stretching supported
• Isolated 3.3 V rail for Qwiic sensors (MPS MIE1W0505BGLVH isolated DC-DC)
• Qwiic / STEMMA QT connector plus a 0.1″ 4-pin header on each side
• 10 kΩ I²C pull-ups on both sides
• Four M2 mounting holes on a compact 33 × 18.7 mm board
• Open-source hardware (CERN-OHL-P v2)

Applications

• Running body-connected sensors (EMG, ECG, GSR/EDA) from a mains-powered computer
• Breaking ground loops between an I²C sensor and its host
• Noisy lab and classroom setups where many hosts share one power strip

Specifications

• Isolator: TI ISO1640BD (8-SOIC) — 3000 V_RMS for 60 s per UL 1577; 450 V_RMS working voltage; basic insulation (component ratings)
• Isolated power: MPS MIE1W0505BGLVH, rated 2.5 kV_RMS (component rating)
• I²C speed: up to 1.7 MHz (Standard, Fast and Fast-mode Plus)
• Host side: 3.3 V from the Qwiic port
• Isolated side: 3.3 V output, up to ~75 mA for connected sensors
• Connectors: 2 × Qwiic / STEMMA QT (1 host, 1 isolated), 2 × 0.1″ 4-pin headers
• Board: 33 × 18.7 mm, 2-layer, 4 × M2 mounting holes

Scope — I²C only

easyISO isolates I²C only. It does not carry SPI or interrupt/data-ready lines, so SPI boards such as the ADS1292R, ADS1293 and ADS1262 breakouts are not served by it.

Important notice

easyISO is a development tool, not a certified medical isolation barrier. The ratings above are the manufacturers’ component ratings, not a board-level safety certification. It is intended for evaluation, education and research only.