Dangerous Prototypes

Other projects => Open Bench Logic Sniffer => Topic started by: truehybridx on June 30, 2014, 05:08:46 pm

Title: 1-wire analysis?
Post by: truehybridx on June 30, 2014, 05:08:46 pm
So for my first adventure with my new logic analyzer is to play with our printers 1-wire connection to its toner cart :P

Now my understanding is that the pwr/io line is constantly high as long as the printer is powered up, and drops low when communicating back and forth. When I open the top of the printer (say to remove the toner cart) it will power that line off and reconnect it once I close the top...

So I figured for that I would set a trigger for when my channel-0 goes high (when i close the top), then a second trigger for when the line goes low.....

Problem is I don't think Im getting anything useful with the settings i have..

I am unsure on which bus mode this thing is using: ether standard (at iirc 15kbps) or overdrive (at 125kbps)
So im guessing for standard I would use a sample rate of 20mhz  and overdrive would be 200mhz?

(I also keep running into a problem where i get back just two samples -_-, is there a way to force the max samples no matter what?)
Title: Re: 1-wire analysis?
Post by: Qwlciguk on June 30, 2014, 10:53:53 pm
For a piddly 15kbps signal, 100KHz sample rate is more than enough.  Similarly, for the 125Kbps signal, 1MHz sample rate is plenty.  Consider using RLE though, if you need a really long capture time.
Title: Re: 1-wire analysis?
Post by: truehybridx on July 01, 2014, 10:53:22 pm
Alright, thx.

I think I am getting useful data now... I guess when it just returns 2 samples i need to reset everything cuz it goes buggy for some reason and will always return 2 samples with all channels low :(


It seems like i can usually get one good read with RLE enabled, then after that i get this 2 sample return nonsense where all the channels are low :(
Title: Re: 1-wire analysis?
Post by: rose on October 27, 2014, 07:46:26 am
The OLS only uses the first 2MBIT and I don;t think the app does anything with that value (beside range check?), so it shouldn't cause issues, but I updated it in the source anyways.

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