Michael Sparks

Sometimes you're asked to deliver something that seems impossible, but necessary in a given timeframe. Sometimes it's several seemingly impossible things.

Developing the prototype for the BBC Micro:bit - a pocket sized, child programmable computer - was very much like this. It had 3 months to be delivered in a form sufficiently robust and usable to be used by children in schools across the country; to be sufficiently documented to be completely understood from scratch by others; and to be a sufficiently open and flexible design to allow any and all parts of the system to change, while retaining its core principles.

There was about 3 months to develop the entire stack from scratch. This included a microcontroller based hardware stack, through firmware, a python to C++ compiler (3-4 weeks), through django website, through to a QT (PySide) client side application, through to publication of the device as a network connected and controllable device via REST. Python was involved in all layers - including at microcontroller level on a device too small to run any python interpreter.

The bulk of the development period had just one developer for hardware and software. For just 1 month there were 2 extra developers brought on board, part time to assist.

This talk will be a detailed overview of the various subsystems, and the strategies taken to deliver a complete, mass produce-able, and sufficiently scalable product such an aggressive timescale. The talk title is a nod to the idea that while each of the various layers is doable alone in 3 months, doing all the layers simultaneously using one developer is ... challenging.

It should be of interest to those interested in developing hardware and software products, and especially those developing products that have both a hardware and software element.