Adding A Serial Trigger To A Logic Analyzer

If you’re attempting to debug a serial bus with a bare-bones logic analyzer, you’re going to have a bad time. Most of the inexpensive analyzers available don’t have a serial pattern trigger, or a way to start recording data after a specific pattern of bits comes down the pipe. [Neil] sent in a great little project that adds a serial trigger to these analyzers, we’ve got to hand it to him for designing such a useful board.

[Neil] designed a small board featuring a CLPD that converts serial data to parallel data. By setting the trigger condition of the logic analyzer to any 24-bit pattern he wants, it’s possible for [Neil] to sniff a serial bus exactly when he wants to.

The circuit is quite minimal, basically just a 100-pin CLPD and a bunch of 0.100″ header pins. It’s a useful tool, and although we couldn’t find the board file to make our own, we’re sure [Neil] will be providing that shortly.

10 thoughts on “Adding A Serial Trigger To A Logic Analyzer

  1. I keep wondering what kind of potential an Altera DE-1/2 board would have as a logic analyzer (granted, you have to do your own interfacing, level conversion, etc. if that’s necessary). Has anyone tried just using a DE1/DE2 devkit with a computer, and maybe some extra parts? I haven’t messed with this, but I’m sure you can use the GPIO pins on a devboard and configure a LogicTap circuit in Quartus (adding your own custom HDL code to process your inputs however you please).

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