Source of Slack

Four 5mm NeoPixels are now installed on the prototyping board. Individually, they work well with the TrinketPro as a controller. Software development is in progress to produce the most usable display. To be most useful, the code needs to make it easy to independently adjust the hold times for full inspiration and full expiration, as well as the times for letting the breath in and out.

The next hardware task is to test the power supply. I've chosen the Adafruit Pro Trinket LiIon/LiPoly Backpack Add-On and a 105mAh Li-Ion battery. A 500mAh battery is also available if more capacity is needed. The NeoPixels can draw quite a bit of current, but maximum brightness is not needed for the application. In fact, it would most likely distract from the purpose, so we'll be running the LEDs at lower current levels.

To improve the display for the project, I ordered a set of 5mm NeoPixels from Adafruit. They arrived quickly and have replaced the original blue LEDs on the protoboard. The NeoPixels will give capability for better control over the hue of the display, and several LED's can be controlled with fewer pins on the Trinket., reducing the rat's nest of wiring that often accompanies LED displays. So far, the biggest problem with using NeoPixels has been locating a schematic for them. The Adafruit NeoPixel Uberguide fails to provide a pinout for the 5mm version. Finally, I found a schematic lurking in the middle of a new product video.

The display will allow information to be conveyed by using a variety of colors as cues. Currently, the plan is to start with a "brighter" color when the breath pacer is first turned on -- probably a shade of yellow. This will indicates to the user that his/her breathing rate is not yet optimal. As the pace is slowed, the display color will move toward green and finally end on blue, indicating that the optimal breath frequency has been reached. At the same time, different LED's in the display will also be activated to indicate inhalation and exhalation.

I now have an Adafruit Trinket Pro (5v) in house for the first prototype. For the time being, blue LED's are being used for the display until an order of multicolor LED's arrives. Today, code for timing function was completed and downloaded. Initial tests show that the code works successfully as a fixed timer for pacing the inhale/exhale breath cycle.

The next step is to code a function that allows information be fed to the Trinket about frequency of his/her current breathing. The user establishes a baseline by pushing a button at the completion of each exhale. The software will calculate current breathing frequency and begin pacing at that frequency. Then the pacing will gradually slow until it matches the target frequency of approximately 6 breaths per minute. This is an important feature of the project. Users often find it hard to slow their breathing to match the target frequency. Custom pacing beginning at the user's baseline is the key to comfortably attaining the very slow breathing rate that produces optimal relaxation.

First we're going to build a simple timer with visual display for pacing the breath, then elaborate the display and perhaps add other sensory modalities such as auditory and haptic signals.

I'm using four LED's in a vertical column. The bottom LED represents a complete exhale and the top LED represents a complete inhale. To provide pacing, I fade from one LED to another. The two middle LED's will indicate that we are between the two extremes.

The next step is to decide how to factor color into the display.