What's This Thing

iButton data loggers, DS1921 Thermochron and derivatives are those little stainless-steel coin-shaped chips that ride along in cold-chain shipments, lab freezers, vaccine coolers, and field experiments, quietly recording temperature (and humidity) for weeks at a time. They're rugged and cheap — but actually using them traditionally means a USB blue-dot adapter tethered to a Windows PC running the vendor's aging 1-Wire software.

ChillPoint throws all of that away. It's a handheld, battery-powered ESP32-C6 device with a 1-Wire probe on the front. Touch an iButton to the probe and the device reads it, parses every register, and stores the result on its own flash. There's no app to install: the device hosts its own Wi-Fi access point an web UI, so any phone, tablet, or laptop becomes the screen.

From the web UI you can:

  • Read an iButton — ROM ID, mission status, min/max, the full datalog buffer, histogram bins, and alarm events, charted in the browser.
  • Configure a new mission — sample rate, alarm thresholds, rollover, resolution.
  • Download the logged data as JSON, or
  • Batch-upload it to a remote "Data Host" HTTPS endpoint for archiving.

Why I built it

The vendor toolchain is the bottleneck. If you have a freezer full of loggers to read out in the field, dragging a laptop and a USB adapter around is miserable, and the desktop software is single-platform and dated. I wanted something I could hold in one hand, tap a chip against, and read on my phone — the way modern hardware should work. The ESP32-C6 has Wi-Fi 6, a generous 8 MB of flash, and enough RAM to host a real web app, which makes the "the device is the server" approach practical.  The hardware schematics and software will be open source.

How it works

Hardware

  • MCU: ESP32-C6 (8 MB flash, Wi-Fi 6 / BLE)
  • Probe: 1-Wire iButton reader
  • Power & timekeeping: RV-3028-C7 RTC and a MAX17048 fuel-gauge battery monitor share the I²C bus
  • HMI: a mode button plus a small bank of status LEDs (mode, config, pass/fail) and a PWM buzzer for audible read feedback
  • Storage: on-board LittleFS — each reading and each mission profile is a JSON file on flash

Current Status

The hardware development is almost finished.  A few more spins for layout issues, and the membrane switch graphics need updating.  There is a pre-launch page on CrowdSupply in case you are interested in the project: https://www.crowdsupply.com/g9six/chillpoint