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Messages - helmy

1
Open 7400 Competition / Re: [Entry] 8-Channel, 6 -MSPS USB logic analyzer!
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 ?
3
Open 7400 Competition / [Entry] 8-Channel, 6 -MSPS USB logic analyzer!
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

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