Logic analyzers are allowing us to monitor and/or diagnose a large number of digital signals simultaneously and these devices are essential when developing complex digital systems. In this project we design simple 8 channel USB logic analyzer with Windows version of driver software.

Prototype of 8 channel USB logic analyzer
Prototype of 8 channel USB logic analyzer

Design of this logic analyzer is based around Future Technology Devices FT245 USB FIFO chip. With the given oscillator this system takes 14MSPS (Mega samples per second) and this system is design to work as (USB) self powered device (without any external power source).

Driver part of this project is based on FTD2XX driver and GUI is developed using Delphi. Current version of driver software is design to work with Windows NT operating systems and it is highly recommended to use it with 1360 × 768 or with higher video resolutions (with aspect ratio of 16:9).

Output of the 8 channel USB logic analyzer
Output of the 8 channel USB logic analyzer

This design also contains real-time logic level indicators to monitor “low frequency” signal levels and construction of that portion is not much essential.

When constructing the circuit take special care about IC1 – 4069 Hex Inverter (in this design it mainly worked as CMOS Pierce - Gate oscillator), because at the time of testing we found that some of the chips may not produce proper output and finally it get affected to the entire system (including driver software). In our prototype we use Fairchild’s CD4069UBCN as IC1.

Project Related Downloads


Complete project source codes, binaries, schematic diagrams and PCB patterns of 8 channel USB logic analyzer

References


FT245BL - USB FIFO
LM339 - Low Power Low Offset Voltage Quad Comparator
CD4069 - CMOS Hex Inverter
CD4093 - CMOS Quad 2 input NAND Schmiitt Triggers