Thank you Jared. I will look at your project and try HIDAPI for my project.
On Thu, Jan 21, 2016 at 4:42 PM, Jared Contrascere <
jared.n.contrasc...@libretees.com> wrote:
> Hi, Chhavi!
>
> I'll defer to other opinions on the matter, but I think pyusb might be too
> low-level for your purposes, Chhavi. I've been able to interface with a HID
> scale on a Raspberry Pi using the python 'hidapi' package. See
> https://github.com/libretees/silverscale for an example project.
>
> --contracode
>
>
> On Thu, Jan 21, 2016 at 3:17 PM, Chhavi Goenka <cgoe...@gmail.com> wrote:
>
>> Hi,
>> I am trying to interface raspberry pi with a custom HID device via USB. I
>> am using PYUSB for this. But once I run my program i get a timeout error.
>>
>> Here is my program:
>>
>> import os
>> import sys
>> import time
>>
>>
>> import usb.core
>> import usb.util
>>
>> packet_len = 64
>>
>> # packet request function
>> def pack_request(*arguments):
>> packet = [0x0] * packet_len
>> i = 0
>> for arg in arguments:
>> packet[i] = arg
>> i+=1
>> return ''.join([chr(c) for c in packet])
>>
>> def show_result(bytes):
>> sys.stdout.write("Result:")
>> sys.stdout.write(''.join(['%d ' % abyte for abyte in bytes]))
>>
>>
>> def main():
>> dev = usb.core.find(idVendor = 0x04d8, idProduct = 0xf2a6)
>>
>> if dev is None:
>> raise ValueError('Device not found')
>>
>> #dev.set_configuration()
>>
>> if dev.is_kernel_driver_active(0):
>> reattach = True
>> dev.detach_kernel_driver(0)
>>
>> cfg = dev.get_active_configuration()
>> intf = cfg[(0,0)]
>>
>> ep = usb.util.find_descriptor(
>> intf,
>> # match the first OUT endpoint
>> custom_match = \
>> lambda e: \
>> usb.util.endpoint_direction(e.bEndpointAddress) == \
>> usb.util.ENDPOINT_OUT)
>>
>> assert ep is not None
>>
>> raw = pack_request(0x00, 0x81)
>>
>> dev.write(1, raw, 100)
>>
>> bytes = dev.read(0x81,packet_len, 10000)
>> show_result(bytes)
>>
>> #print(bytes)
>>
>> if __name__ == '__main__':
>> main()
>>
>>
>> and Here is the error:
>>
>> pi@raspberrypi:~/Documents $ sudo python multispec_usbcode_jan21.py
>> Traceback (most recent call last):
>> File "multispec_usbcode_jan21.py", line 66, in <module>
>> main()
>> File "multispec_usbcode_jan21.py", line 58, in main
>> dev.write(1, raw,100)
>> File "/usr/local/lib/python2.7/dist-packages/usb/core.py", line 878,
>> in write
>> self.__get_timeout(timeout)
>> File "/usr/local/lib/python2.7/dist-packages/usb/backend/libusb1.py",
>> line 778, in intr_write
>> timeout)
>> File "/usr/local/lib/python2.7/dist-packages/usb/backend/libusb1.py",
>> line 856, in __write
>> _check(retval)
>> File "/usr/local/lib/python2.7/dist-packages/usb/backend/libusb1.py",
>> line 552, in _check
>> raise USBError(_strerror(ret), ret, _libusb_errno[ret])
>> usb.core.USBError: [Errno 110] Operation timed out
>>
>> Please let me know how to get around this?
>>
>> Thanks,
>> Chhavi
>>
>>
>>
>>
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>
>
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