Sip/Puff Sensors
The Sip/Puff Sensors on the mouthpiece and the tube on the side of the joystick can each sense vacuum or pressure over a range of +/-2kPa (4 inches Water Column) and measure the analog value to categorize the strength as high or low, for a combination of four signals per sensor, hard and soft, sip or puff. This gives twenty-four possible sip/puff combinations when various combinations of individual and multiple holes are used. When a sensor is active, an LED lights to give feedback to the user. Red for puff and Blue for sip.
When the user sips or puffs the Quadstick will make either a click or beep to indicate it detected a hard or soft sip/puff, respectively. The hard sip/puff is detected the moment the pressure exceeds the high threshold.
To avoid triggering a soft sip/puff signal while applying a stronger pressure, an adjustable delay (default 1200ms) is used to allow time for the pressure to move out of the soft region, to the hard region, before generating the signal. While the pressure is in the soft region, the corresponding status LED flashes and an audio tone, which varies with pressure, is produced, to give the user feedback about the pressure they are applying.
Once the time delay has expired a beep sound will indicate the signal has been triggered. Once triggered, the Soft signal latches and the pressure must return below the Deactivation Threshold before the signal will release. When either Soft or Hard pressure signals are active, the pressure above the higher threshold can be used as an analog value, like with a Gamepad Joystick or Trigger. If the Soft pressure zone for a particular tube is not used, the audio tones are suppressed. The time delay is adjustable and some users shorten the delay to a few tenths of a second to activate soft sip/puffs more quickly.
