Firefly Design LLC

Product Design Consulting

Fireflies are Amazing

Posted by denisbohm on April 01, 2013. 1 Comment


Here are some fun firefly facts that I collected a while ago...

Fireflies aren't really flies and glowworms aren't really worms. Fireflies (or lightning bugs) are soft-bodied beetles in the family Lampyridae.

Glowworms are actually young fireflies, the luminous larvae that squirm forth from firefly eggs. These grublike wonders live in the ground eating slugs and snails for almost two years until they metamorphose into pupa, and then fireflies.

Fireflies are mostly active at night when they zoom around flashing their taillights and eating nothing.

Fireflies use the light on their lower abdomen segments to attract mates. (Since glowworms don't mate, no one knows exactly why they glow.) Fireflies of the same species recognize each other by the number of flashes used, the frequency of flashes and the color of the light.

Different species emit different colors of light such as green, amber, or yellow.

The light fireflies produce (or that any living organism produces) is called bioluminescence. It's a chemical process in which luciferin reacts with oxygen in the presence of an enzyme called luciferase. Chemical energy from the reaction is transformed into light.

Close to 100% of the energy from the chemical reaction is given off as light. For comparison, a typical light bulb give off only 10% of its energy as light, while the rest is wasted as heat.

Fireflies control the rate of their light flashes by admitting air into the luminescent organs.

All known firefly species are bioluminescent as eggs and larvae, but some are adults are not.

Some Asian species are fully aquatic and live underwater.

Fireflies larvae are predators and feed mostly on earthworms, snails, and slugs. They can detect snail or slug slime trails and follow them to the prey. An anesthetic type substance is injected into the prey to immobilize it.

Firefly larvae live one to two years, spend about 10 days as a pupa, then live as adults for only a few days to a week.

Adult fireflies don't bite, have no pincers, don't attack, don't carry disease, and are not poisonous.

Firefly larvae use their luminescence as a warning signal that communicates to predators that they taste bad because they have defensive chemicals in their bodies.

Adult fireflies use a species specific flash pattern to attract a member of the opposite sex.

In some species the female is wingless.

When fireflies are distressed they flash to warn others.

In some species, the female firefly mimics the flash of another species. When the male responds and comes to her to mate, she eats him instead.

There are about 2,000 known species of fireflies.

Fireflies are also known as Lighting Bugs.

Firefly Ice: Development Enclosure

Posted by denisbohm on March 22, 2013. 0 Comments

The Firefly Ice development enclosure is a very simple 3D printed enclosure that will be used to protect the PCBA while testing it out in real world scenarios.  This enclosure is easy to take apart for reprogramming the PCBA via the ARM SWD pads.  The custom parts are very inexpensive to produce in small quantities via 3D printing services such as Shapeways.

The renderings below show the Firefly Ice development enclosure along with some of the internal parts.  The PCB is represented by the green shape.  LEDs and Micro USB port are visible in the top view.  The coin cell battery option is visible in the bottom view.



Firefly Ice: Prototypes

Posted by denisbohm on March 20, 2013. 0 Comments

Printed Circuit Board Assemblies

The first 10 Firefly Ice prototype printed circuit board assemblies (PCBA) have been ordered.  All the components have arrived and the printed circuit boards are currently being fabricated.  The complete PCBAs are scheduled to arrive in early April.  The hardware will then be tested for functional correctness and expected power consumption.  If revision is required, another prototype build will be started at the end of April.

Development Enclosure

A very simple 3D printed enclosure will be used to protect the PCBA while developing the device and testing it out in real world scenarios.  This enclosure will be very easy to take apart for reprogramming the PCBA via the ARM SWD pads.  These will be very inexpensive to produce in small quantities via 3D printing services such as Shapeways.


Once the hardware is checked out, the development focus will shift to the firmware, data uploading app, and cloud storage.

Open Source Activity Monitor: Firefly Ice

Posted by Denis Bohm on March 18, 2013. 0 Comments

The Firefly Activity Monitor project is developing an open source activity monitor. The electronics, mechanicals, firmware, uploading, and cloud storage are all open source.

The first design produced, the Firefly Ice, is intended to be a general purpose device that can be used to develop the whole flow through the basic system.  When all the hardware and software is complete for this first design then more variants will be produced.  Two new variants under consideration are a small low cost version and a very thin waterproof version.

The Firefly Ice activity monitor will have the following features:


  • ARM Cortex-M3 Processor with 256KB Flash & 32KB RAM
  • Bluetooth Smart Radio
  • Full Speed USB
  • 3-Axis Accelerometer
  • 3-Axis Magnetometer
  • Temperature Sensor
  • Coin Cell or Rechargeable Lithium Polymer Prismatic Battery
  • LED Indicators (2 RGB + 8 Red)
  • 64KB Nonvolatile Storage
  • Real Time Clock
  • Very Low Power Sleep & Active Modes


  • Calculates & Stores Activity Metric
  • Commands & Data Transfer Via Bluetooth & USB
  • Encrypted Communication
  • Connection Status Indication
  • Charging Status Indication
  • Diagnostics Log


  • Automatically Set Device Time
  • Transfer Activity Metrics to Cloud
  • View Activity Metrics Chart
  • Real Time Display of Accelerometer & Magnetometer Data


  • Stores Activity Metrics
  • Push Notifications
  • Authorization
  • View Activity Metrics Chart
  • View Diagnostics Log

Open Source Activity Monitor: Not Everything is Steps

Posted by denisbohm on March 15, 2013. 0 Comments

Adult oriented activity monitors have become quite popular.  Nike+ FuelBand, Jawbone Up, FitBit, and many more.  These are great devices and they do track more than just steps.  However, their primary focus is adult oriented exercise.

There are many more applications for activity monitors.

For example:

  • Am I in the right body posture while learning a new a yoga exercise?
  • How synchronized am I with my rowing team?
  • What inclines did I encounter on this new cycling route?
  • How many laps did I swim last week?
  • How smooth are my dancing moves?
  • How active are my tweens while in random play?

And of course activities that aren't about people:

  • How active are my pets when I'm home versus away?
  • Have my cats eaten and gone to the bathroom on their regular schedule?
  • How much wobble is there in my football throw?
  • Has the outside door been left open?  Is it flapping in the wind?
  • Did I leave the garage door open for an extended length of time?
  • Is the laundry in my garage finished?
  • Is a product being used?  What position is it in?  How is it being moved?

Can you use the Nike+ FuelBand, Jawbone Up, FitBit, etc, for all of these applications?  The answer is a clear no.  Those devices record very specific information that won't work for these other applications.  None of those devices allow their firmware to be changed for other purposes.  All of those eco-systems have their own methods for transferring data to their cloud, storing the data in their system, and accessing it via their APIs.

The Firefly Activity Monitor project is developing an open source activity monitor. The electronics, mechanicals, firmware, uploading, and cloud storage are all open source.  Nothing is locked behind any vendor's proprietary eco-system.  Pre-built Firefly hardware will be available.  You can change the firmware for your application.  The hardware can be modified to suit your needs.  Add new sensors, change the power system, use a different radio.  Create new form factors: wrist band, band-aid, or a pebble for your pocket.