usb device busy (ACR122U-A9)

Asked by BERGER Stéphane


I designed a program which is nanaging ten tags reader . Sometime, when the system starts, and an tag is on a reader, the contactlessFrontend failed and after my reader is busy ; How I can reset the device ? I

best regards,


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BERGER Stéphane
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Stephen Tiedemann (stephen-tiedemann) said :

Unfortunately when a device can not be opened there is no way for nfcpy to send any reset commands. The only way is to cut power, a.k.a. unplug from USB. Some USB hubs allow to set port power state - that would allow this in software. Software like or may do the trick. On Raspberry Pi 3 I could switch off the power from the Broadcom SOC USB port with "echo 0x0 > /sys/devices/platform/soc/3f980000.usb/buspower" to unpower the connected USB Hub IC.

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BERGER Stéphane (s.berger) said :


Thanks, your answer confirms that I read . So I fixed my problem, the issue was I stopped the process which was checking if a tag is here, but without be sure the call to connect was finished . So, a the end, the usb still busy. Then I restarted my programm, the contactlessFrontend failed for this reason.
So now, my process stop when the connect call is finish and all work fine.

thank for all,