Anyone that knows me knows I love a good hardware hack. The thing about working with hardware, especially hardware that you didn’t build, is that it isn’t always easy to figure out what lines go to what and where you need to tap your project into.
Saleae Logic 4 to the rescue. This logic analyzer allows you to tap into a circuit and see what is being transmitted over it. It’s extremely useful and I can anticipate this being in my hardware hacking tool kit for the foreseeable future. To demonstrate the potential of this device I setup a little Arduino project.
Setting up the Arduino project is simple. This just consists of the basic Arduino blink example with one addition. In the code if you look you will see I am also outputting serial data.
The Serial line is set to a baud rate of 9600 (this will be important later in this tutorial). Every time the code loops, it prints “Hello Anthony to the serial line and also toggles the LED either on or off.
With this basic code we can demo both the Digital reading capabilities of the logic analyzer but also the analog capabilities as well.
As you can see in these photos, I have attached some leads to our Arduino project. I have a lead connected to the positive pin of the LED, a lead attached to a wire coming out of TX on the Arduino and finally a lead connected to the ground of the Arduino.
These leads are connected to our Saleae Logic Analyzer and will allow us to pump data back into their software on my dev machine. Then we can analyze the data to debug it or look for specific identifiers that will help us identify the lines we are attached to.
Once we record the data we can analyze it in the provided software. This software will automatically decipher serial data for you. As pictured below, you can see that the text Hello Anthony is being deciphered above the actual analog readings that we recorded. How cool is that!
This device is incredibly cool. I highly recommend anyone attempting to reverse engineer devices pick up one of these analyzers. They’re very easy to use and honestly, they are pretty fun to play with.
Author: Anthony Russell
Professional .NET developer