sreeja gupta

full stack developer!?

Rapidly Prototyping a Smart Tote Bag for Hopper Down Under

2019-06-24 sreeja guptaiot

Hopper Down Under invited Inny and me to present a workshop at the end of July, and we’re super excited!

We did a version of this IoT workshop for the Grace Hopper Celebration of Women in Technology in Orlando back in 2017, and it was a resounding success if I do say so myself. The line don’t lie:

Long line of people waiting to get into our talk at GHC 17, Orlando

Preparation for Orlando was done in a frantic rush, and we learned lots of lessons and burned lots of hair along the way.

This time, we’re a lot calmer. We have a plan. Our hair is significantly less singed. We’re nailing this conference prep business.

The Initial Proposal

Our initial conference proposal for Hopper Down Under 2019 was to:

  • Create a micro-controller enabled tote bag written in C equipped with a colour sensor.
  • The LED lights on the tote bag would light up to match whatever you were looking for in the shops. Buying an orange? Bring it close to your bag, and see the lights on it light up!
  • It would all be connected together with Bare Conductive Paint instead of wire circuitry - a true wearable electronics primer!
  • Take workshop attendees through progressive steps on how to make the bag light up.

Seems simple enough, right? We thought so, so we started rapid prototyping.

Initial prototyping of circuit on a breadboard with lots of alligator clips

Alligator clips for days

Learnings (i.e. Hurdles, Challenges, Fuck-Ups)

It’s been two months and we’ve already faced some interesting hurdles along the way.

  • The microcontroller we wanted to use (Adafruit Gemma M0) wouldn’t fit all the complicated and heavy colour sensor code and LED libraries on it. 😡
  • Bare Conductive Paint on cloth conducts about as well as lines drawn in Sharpie 🤦🏽‍♀️
  • The code was in C and quickly became too complicated for beginners 🤷🏽‍♀️

LED lights blinking on and off on a breadboard circuit

Prototyping the colour sensor and accidentally developing an LED blink based language along the way

How The Initial Proposal Is Evolving

Inny and I adapt and adapt QUICKLY. It’s what I love about us.

  • Analog Photocell Sensor > Digital Colour Sensor

    Our tote bag now comes equipped with an ambient light sensor. Too dark while you’re out shopping? Never fear, the lights on your tote will automatically light up to show you the way.

    Benefits: Simpler, cheaper circuit; Easier to code; All the code now fits on the microcontroller’s memory;

  • Conductive Tape > Conductive Paint

    We are using conductive tape instead of paint. The circuits that use tape look adorable.

    Benefits: Resilient & robust circuitry; Easy to pre-assemble; Curious workshop attendees can also mess with the circuit on the day; Circuit looks cute af;

  • Python > C

    CircuitPython is a Python library which you can load onto your Adafruit Gemma M0 and it gives you a full Python REPL and dev capabilities.

    Benefits: Hot reloading of code directly onto the microcontroller; Fast feedback; Better developer experience;

How It Looks Right Now

Here it is in all its prototypal glory. Notice Inny’s hand simulating darkness by covering the photocell:

A gif of a hand hovering over the sensor to make the ambient light darker, which the LED on the circuit light up automatically

Now to make 40 of these and put them on tote bags.

Things To Do In The Next Month 🏃🏽‍♀️

  • Publishing the workshop tutorial materials!
  • Make our IoT enabled tote bags!
  • GIFs of our final tote bags!
  • Show up at conference and do the thing!

I’ve Been Tweeting A Lot - Follow Our Journey!