How to Hack Firmware

4Caster with Hacked Firmware Dave Prochnow

If you've ever wanted to learn how to hack a circuit's firmware, a great beginning point would be SparkFun Electronics. Many of the development, prototyping, and sensor products sold by SparkFun come equipped with a special programming interface. Even better, most of these products feature downloadable firmware. Therefore, with just a modest amount of effort, you can modify one of these products' firmware, reprogram the circuit, and create your own customized product.

You can add your name to a splash screen, develop a new product feature, or -- living life on the edge -- rewrite the whole shebang and make an entirely new product: the sky's the limit when hacking firmware. There is one very important caveat, though: if you don't know what you're doing when tinkering with firmware, you could destroy the product.

In this introduction to firmware hacking, let's try a simple modification. We'll reformat the output from the USB Weather Board v1 so that it can be meaningfully displayed on a serial-enabled 20x4 LCD.

In its stock configuration, the output from the USB Weather Board is a continuous string of numbers, like
#47.25,081.23,026.5,079.70,101723,76$i.

Not very friendly, is it? We'll modify the firmware so that the output is easier to comprehend. Something like:
1.Humidity=47.25% 2.Temp=81.23F 3.Press=101723Pa.

But wait; there's more. We'll also add an LCD for displaying this new output and a battery power supply, and wrap everything up in a handheld enclosure. The result is a portable, handheld personalized weather forecasting system. Or, as I've dubbed it: the 4Caster 1000.