Petrel Firmware V21

Petrel Firmware V21

Petrel Firmware V21 has been released.

Download it here:

Please read the Shearwater Desktop/Firmware Update FAQ, as the firmware update format has changed.

Firmware v21 is a minor update to address a few issues and does not add new features.
Updating from v18 is not necessary unless affected by the issues below.

DiveCAN Rebreather Controller Models

  • CHANGE: Removed auto-promotion of setpoint from 0.19 to lowsetpoint when wet.
    Reminder that the 0.19 setpoint is not intended foruse when breathing on the loop. The 0.19
    setpoint is a convenience feature for use when setting up and storing the rebreather only.

EXT Model

  • CHANGE: When the “Cal FO2” setting is changed, no longer deletes the existing calibration data
    to force a new calibration.

All Models

  • CHANGE: No longer suggests a better gas (by changing displayed gas color to yellow) if the O2
    content is the same (this can only happen if O2 content is the same, but Helium content is
    different). Not a typical situation, but encountered occasionally by divers, who found the better
    gas suggestions confusing.
  • FIX: When switching to/from OC Rec mode, now immediately updates the ‘Altitude’ setting (in
    OC Rec mode this setting can only be set to ‘Auto’). Previously this change would occur after the
    next on/off cycle following the mode change.
  • FIX: For the 1.5V Photo Lithium battery type, fixes an issue where the battery bar graph always
    showed 100%. The low battery warnings and color coded alerts were correct however.
  • FIX: Fixed a problem that could cause “Watchdog Reset” when the battery is changed, especially
    when battery removed for a few hours.

For a complete listing of changes and more information, please read the release notes here: