homemade OLed HUD for CCR Rebreather

Why building a HUD itself?

The HUD on the market are usually implemented with one or more single or multi-colored LED’s. An article on rebreatherworld.com came the idea of a HUD from a miniature OLED build.


I found them in a large auction house and obtained a 0.95 “color OLED graphic. It uses the SSD1331 controller for which there was already finished in the net libraries (www.microcontroller.net).

Served as control electronics, the circuit foundation stone of the dive computer.  However, it should all fit in a “can” of TecMe.
Therefore, the circuit has been realized in SMD.

In the can even fit a standard battery LiIo what the power supply of course easier.

What features has the OLED_HUD

  • The operation is done inside the enclosure via a “joystick” to perform the “Select”, “up”, “down”, “Yes”, “No”.
  • Manual brightness adjustment of the display
  • Displays battery voltage
  • Display height above sea level (barometric altitude formula)
  • Display of three oxygen sensors in a large font
  • Show the cell voltage in a small font
  • Calibration with Air
  • Calibration with 100% O2
  • Altitude mode selection in 500m steps
  • Power off (Sleep Mode)

The display then changes its colors of pO2:

RED: is <0.65 and> 1.5

YELLOW: when> = 0.65 to <1.1 and> 1.3 to <= 1.5

GREEN: when> = 1.1 and <= 1.3

The heading “pO2” will change your color accordingly, being always the “most” dangerous color appears.

The OLED HUD electronics.
The display in detail. It is attached to a Dolphin mouthpiece. Possible to see the three sensors in pO2 (red) behind the sensor voltages.

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