[libhid-discuss] Inconsistency while reading data from the usb device

Post by shiva vadla
Hello All,
I am trying to read the card data from a credit card reader (usb device)
using interrupt endpoint. I can open and claim the hid interface and read
the data from the card reader. But if I close and delete the hid interface
after i am done reading and try to read the data again for the next card
swipe, i miss the first packet (8 bytes) of the data on every alternate
read. I am not sure why this is happening. If i do not close the hid
interface and keep my program running, i do not see any issues. Any help is
appreciated.

Just a guess, what if you reset the hid interface before closing
the interface?

--
Xiaofan

shiva vadla

2010-12-09 17:48:32 UTC

Thanks for the response. I have just tried that, but I still see the same
issue. Any suggestions?

interface

Post by shiva vadla
after i am done reading and try to read the data again for the next card
swipe, i miss the first packet (8 bytes) of the data on every alternate
read. I am not sure why this is happening. If i do not close the hid
interface and keep my program running, i do not see any issues. Any help

Post by shiva vadla
appreciated.

Just a guess, what if you reset the hid interface before closing
the interface?
--
Xiaofan

--
Shiva
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Xiaofan Chen

2010-12-10 03:27:28 UTC

Post by Xiaofan Chen
Just a guess, what if you reset the hid interface before closing
the interface?

Thanks for the response. I have just tried that, but I still see the same
issue. Any suggestions?

Manuel F Martinez

2010-12-10 06:11:54 UTC

Are you able to post your code? maybe it can help everyone to see what you
are trying to accomplish.

Thanks,

Post by Xiaofan Chen
Just a guess, what if you reset the hid interface before closing
the interface?

Thanks for the response. I have just tried that, but I still see the same
issue. Any suggestions?

Sorry I have no idea. Maybe you want to ask in the Linux usb mailing
list cause I do not think this is a libhid/libusb issue, but rather a
usb device issue. They will probably ask you to provide the
usbmon log or things like that.
--
Xiaofan
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--
Manuel F Martinez
Linux Systems Engineer
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shiva vadla

2010-12-10 16:24:08 UTC

I think it's the kernel issue. I was trying it on CentOs 2.6.18 and it
wasn't working. But when I tried on OpenSuse 11.3, it works fine. Thanks all
for your help.

Post by Manuel F Martinez
Are you able to post your code? maybe it can help everyone to see what you
are trying to accomplish.
Thanks,

Post by Xiaofan Chen
Just a guess, what if you reset the hid interface before closing
the interface?

Thanks for the response. I have just tried that, but I still see the

same

Post by shiva vadla
issue. Any suggestions?

--
Manuel F Martinez
Linux Systems Engineer

--
Shiva
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Manuel F Martinez

2010-12-11 07:52:50 UTC

Good to hear that, anyways, feel free to post your code if you still want to
try CentOS, I'll be happy to help.
I successfully build apps for some USB devices on CentOS 5 with 2.6.18
kernel.

Thanks,

Post by shiva vadla
I think it's the kernel issue. I was trying it on CentOs 2.6.18 and it
wasn't working. But when I tried on OpenSuse 11.3, it works fine. Thanks all
for your help.

Post by Manuel F Martinez
Are you able to post your code? maybe it can help everyone to see what
you are trying to accomplish.
Thanks,

Post by Xiaofan Chen
Just a guess, what if you reset the hid interface before closing
the interface?

Thanks for the response. I have just tried that, but I still see the

same

Post by shiva vadla
issue. Any suggestions?

--
Manuel F Martinez
Linux Systems Engineer

--
Shiva

shiva vadla

2010-12-13 19:55:23 UTC

Here is the code. I am using java to load the libhid library and talk to the
device.

LibHid libHid = LibHid.libHid;

libHid.hid_set_debug(HIDDebugLevel.ALL);
libHid.hid_init();
LibHid.HIDInterfaceMatcher hidMatcher = new
LibHid.HIDInterfaceMatcher((short) 0x0801, (short) 0x0011, null, null, 0);
libHid.hid_force_open(hidInterface, 0, hidMatcher, (short) 3);
libHid.hid_interrupt_read(hidInterface, 0x81, output, 887, 0);
libHid.hid_close(hidInterface);
libHid.hid_delete_HIDInterface(hidInterface);
libHid.hid_cleanup()

Thanks!

Post by Manuel F Martinez
Good to hear that, anyways, feel free to post your code if you still want
to try CentOS, I'll be happy to help.
I successfully build apps for some USB devices on CentOS 5 with 2.6.18
kernel.
Thanks,

Post by shiva vadla
I think it's the kernel issue. I was trying it on CentOs 2.6.18 and it
wasn't working. But when I tried on OpenSuse 11.3, it works fine. Thanks all
for your help.

Post by Manuel F Martinez
Are you able to post your code? maybe it can help everyone to see what
you are trying to accomplish.
Thanks,