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#1 2012-11-08 01:36:24

marcv81
Contributor
Registered: 2012-07-31
Posts: 12

Inconsistent USB communications

Hi,

I ran the client software on 3 different Linux machines and I had quite a few problems with the USB.

- 1st device works perfectly.

- 2nd device misses a few answers from the Proxmark, below are the results of 2 'hw tune' commands run successively.

proxmark3> hw tune
#db# Measuring antenna characteristics, please wait..                 
proxmark3> hw tune
#db# Measuring complete, sending report back to host                 
         
# LF antenna:  0.00 V @   125.00 kHz         
# LF antenna:  0.00 V @   134.00 kHz         
# LF optimal:  0.00 V @ 12000.00 kHz         
# HF antenna: 14.98 V @    13.56 MHz         
# Your LF antenna is unusable.         

- 3rd device misses all the answers from the Proxmark. I can see that the commands are sent correctly because the LEDs flash appropriately but nothing ever gets sent back to the client.

Has anyone else encountered such a behaviour? Is there anything I could try to tune in the code to fix the problem (i.e.: latencies, etc.)? Any other general comments?

Cheers,
Marc.

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#2 2012-11-08 08:10:00

Cex
Contributor
Registered: 2009-12-14
Posts: 104

Re: Inconsistent USB communications

You need to wait for the first command to finish before issuing a new one.
The USB is polled in the Atmel, so your commands will be lost or corrupted as the Atmel won't read the USB until it finishes with current command.

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#3 2012-11-08 10:48:16

marcv81
Contributor
Registered: 2012-07-31
Posts: 12

Re: Inconsistent USB communications

Thanks for your answer Cex.

On the second device I left a long gap between the 2 commands. I am able to verify the appropriate execution of the commands monitoring the LEDs too.

So I don't believe I ran into the problem you describe. My problem is that despite the Proxmark running correctly the PC does not receive all the results the Proxmark sends back. I ignore if the issue is PC related or Proxmark related.

Cheers,
Marc.

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#4 2012-11-09 02:52:30

marcv81
Contributor
Registered: 2012-07-31
Posts: 12

Re: Inconsistent USB communications

On the 2nd computer that worked intermittently I fixed the problem using libusb1.0 in the client instead of libusb-0.x
Unfortunately the same trick did not fix the issue on the 3rd computer.

Cheers,
Marc.

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#5 2012-11-13 01:53:35

marcv81
Contributor
Registered: 2012-07-31
Posts: 12

Re: Inconsistent USB communications

Turns out it had nothing to do with libusb-1.0 vs. libusb-0.1. The patch I applied to use libusb-1.0 also changed the USB read/write timeouts, and that's what made the difference. If you experience issues with the USB I suggest changing the timeouts in client/proxusb.c to 5000 (the original values are 1000 and 500).

Cheers,
Marc.

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