We aren’t sure what’s coolest about [Richard Testardi’s] Flea-Scope. It costs about $13 plus the cost of making the PCB. It operates at 18 million samples per second. It also doesn’t need any software — you connect to it with your browser! It works as an oscilloscope, a logic analyzer, and a waveform generator. Not bad. The board is basically a little life support around a PIC32MK and the software required to run it.
Of course, for $13, you need to temper your expectations. One analog input reads from -6 to 6V (hint: use a 10X probe). The goal was for the instrument to be accurate within 2%. There are also nine digital inputs sampled simultaneously with the analog sampling. The signal generator portion can output a 4 MHz square wave or a 40 kHz arbitrary waveform.
If you need more channels, the board can cooperate with other boards, which is interesting — who doesn’t want a scope you can add a new channel to for $13 each? The little board also has a Basic programming system built-in that includes an editor, compiler, debugger, and file system so that you can script the entire thing that way.
Honestly, we aren’t sure using this as a scope appeals to us as much as using it as a building block for other things. The fact that you can chain them and it has its own web interface means you could probably build some interesting things with it. [Richard] notes that he has one controlling his reflow toaster oven, for example.
You can find similar offerings commercially that have better specifications but, naturally, they don’t cost under $20. Creating a simple logic analyzer is fairly easy with today’s high-performance CPUs, but there are still a few details to consider regarding stability and triggering.