The newer OSTC+ (2026 and later) and OSTC Nano models require a Bluetooth Low Energy (BLE)-compatible updater to update the firmware. While the OSTConf iOS app or the latest HWOS Config for Android (to be released shortly) can perform this task on your mobile device, the old OSTC Companion is unable to do so on desktop computers. We recommend updating via Subsurface here:
https://subsurface-divelog.org/
Here is a step-by-step manual how to do it:
- Pair OSTC with your System from the system's Bluetooth settings (Optional but this makes pairing with Subsurface quicker - at least with Windows 11)
- Download and unzip the firmware file from
https://hwdiving.com/firmwares/
Step 1: Select "Change settings on dive computer" from the Menu
Step 2: Select OSTC 2/3Plus from the list and click on "Select Bluetooth Device"
Step 3: Click "Scan" and select the OSTC from the list. Click "Save"
Step 4: Wait until "Connected to device" is shown at the bottom, click "Update Firmware". Select the update file (.HEX file) from your PC
Step 5: Wait. The Update via BLE will take ~60 seconds. The OSTC will reboot into the new firmware automatically.