I was planning a PC based logic analyzer. The idea is using a cache like sram (like 7cy199 or similar) and storing in it digital samples at high speed (40MHz) for later download to PC via PC port. First experiments demostrate concept is ok, but over 5MHz, strange digital noise appears.
Some circuit or trick?
I was planning a PC based logic analyzer. The idea is using a cache like sram (like 7cy199 or similar) and storing in it digital samples at high speed (40MHz) for later download to PC via PC port. First experiments demostrate concept is ok, but over 5MHz, strange digital noise appears.
Some circuit or trick?
Elektor published a complete logic analyzer based on this concept (fifo ram) some months ago. can scan it if you want it... warning the text is in french ! (the schematics are universal)
You could also take a look on Bitscope, http://racket.bitscope.net/
BitScope is a low cost, high bandwidth, mixed signal oscilloscope and logic analyzer for PC with open hardware design.
If you have problems over 5Mhz it could be ground or decoupling problem
Here is the description of a 100MHz logic analyzer.
I am still working on it because it is not very easy to find a fast FPGA.
You can contact the author and try to buy the PCB (only 30 USD).