[Entry] 8-Channel, 6 -MSPS USB logic analyzer!

[Entry] 8-Channel, 6 -MSPS USB logic analyzer!

Postby helmy » Fri Oct 21, 2011 12:52 am

when i knew about the Open 7400 Logic Competition and saw the prize included a Bus Pirate, i thought why not build something with similar functionality out of 74 chips !

I have a bunch of Prolific PL2303 USB-to-Serial port adapter laying around, this is a very popular IC and from testing it can go all the way up to about 6 MSPS even though the datasheet dose not say that !

what the circuit here dose is take 8 parallel inputs and outputs a valid TTL RS232 signal that can be fed directly to the PL2303 RX pin, all the circuit needs a clock signal with the same baud rate as set in the software , i thought about including a micro controller to generate a clock signal that can be controlled from the computer software, but that would add more non 74 ICs to this circuit !
anyway ,

after thinking about it i decided to use the PL2303 to generate the Clock signal too, and that it by constantly sending out a series of 0 and 1s out of the TX pin , and that is done by the computer software


the circuit diagram is attached to this post
Attachments
Logic.JPG
Circuit.JPG
helmy
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Re: [Entry] 8-Channel, 6 -MSPS USB logic analyzer!

Postby helmy » Fri Oct 21, 2011 1:08 am

Some notes :
if its not clear how you would connect the PL2303 to this, all you need to do is connect the PL2303 RX pin the the SerOut and connect the PL2303 TX pin to the CLK

The U10 Pin 3 is connected to U1 pin 6
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Re: [Entry] 8-Channel, 6 -MSPS USB logic analyzer!

Postby helmy » Mon Oct 24, 2011 1:56 am

today i have managed to connect the circuit successfully to my mobile phone (Nokia N900) , i will be working on the software to capture the data and display it on the phone screen, so now i have a portable logic analyzer that fits into my pocket !

thinking about opt-isolating all the signal inputs, any ideas ?
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