The firmware for the TeHyBug 18650 Universal, Mini TeHyBug and GumBoard (fully written in C/C++, with easy over-the-air updates) has had a big update. Here’s what’s new for you.
๐๏ธ Log data offline โ no server, no network
With a DS3231 RTC + EEPROM module attached, your TeHyBug can now record readings right on the device, completely offline:
- One file per day, a full month retained โ each entry tagged with its full calendar date.
- Pick exactly what to log with placeholders (e.g.
%temp% %humi%); a compact on-device format fits more entries. - Offline mode runs with WiFi switched off for the lowest possible power draw โ perfect for long battery deployments where there’s no network.
- Configure and read everything on the new Data Log page in the web interface.
๐ ๏ธ Easier, clearer setup
- Inline help under every setting on the configuration pages โ no more guessing what an option does.
- More reliable return to config mode from offline / deep-sleep modes after a reset.
- A new Downloads & Changelog page so you can see exactly what each release adds.
โ Reliability fixes
- The blue LED now reliably shows config mode on every boot.
- Offline mode no longer falls back to WiFi when the EEPROM is present.
- A day file reused in a new month no longer mixes dates.
- The dashboard sensor table is no longer cleared right after connecting.
- The offline fallback page now shows the device’s IP address.
- Factory reset now also erases the on-device data log (RTC + EEPROM).
- Saving the Data Log page no longer drops the device out of config mode.
How to update
โ ๏ธ Only update when you need to. If your TeHyBug is working fine, there’s no need to chase every release โ update when a new feature or fix actually matters to you.
Update over the air from the device’s web interface โ open http://tehybug.local/update (or http://<device-ip>/update), sign in, and upload the latest firmware. Keep the device powered during the update; it reboots itself when done.
Prefer to flash over USB? You can use the bundled BugZapper flasher, the Arduino IDE, or esptool โ see the documentation for details.
Compatible with the TeHyBug 18650 Universal (v1 / v2), Mini TeHyBug and GumBoard, and generic ESP8266/ESP8285 boards. Offline logging needs the RTC + EEPROM module.
Questions? Tap the AI assistant on tehybug.com or check the FAQ. Turning ideas into smart devices.

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