I'm trying to connect my Raspberry PI to Pic4550 via USB. (Pic function is ok with windows c# program!). So I have installed rpi 2, pyusb, and tried to communicate with the help of [https://github.com/walac/pyusb/blob/master/docs/tutorial.rst][1]
I get connected to the USB device, lsusb shows:
Bus 001 Device 006: ID 04d8:0080 Microchip Technology, Inc.
The python prog finds the device! Gets the right config but cannot write message:
usb.core.USBError: [Errno 16] Resource busy
I tried to run as sudo, I have added rule:
SUBSYSTEM=="usb", ATTR{idVendor}=="04d8", ATTR{idProduct}=="0080", MODE="666"
Anyway I get the same resource busy
Any glue-help-link?
For other rookies like me I post my solution. To sum up: read docs carefully.
Python: 3.2
PyUSB 1.0
Endpoint is a HID device.
Here is my code working properly.
import usb.core
import usb.util
import sys
from time import gmtime, strftime
import time
print ("Meteo kezdés",strftime("%Y-%m-%d %H:%M:%S", gmtime()))
# find our device
dev = usb.core.find(idVendor=0x04d8, idProduct=0x0080)
# was it found?
if dev is None:
raise ValueError('Device not found')
else:
print ("meteo megvan!")
reattach = False
if dev.is_kernel_driver_active(0):
reattach = True
dev.detach_kernel_driver(0)
endpoint_in = dev[0][(0,0)][0]
endpoint_out = dev[0][(0,0)][1]
#print ("endpoint_out",endpoint_out)
#print ("endpoint_in",endpoint_in)
# write the data
msg = b'\x81'
while 1:
try:
endpoint_out.write(msg)
# reading
#print ("Waiting to read...")
#print (endpoint.bEndpointAddress)
data = dev.read(endpoint_in.bEndpointAddress, 64, 1000)
DHT11_H = data[0] # a tobbi helyiertek kimaradt!!
DHT11_R = data[4]
BMP180_H = data[8]
BMP180_P = (data[12]+data[13]*256+data[14]*65536)/100
print (strftime("%Y-%m-%d %H:%M:%S", gmtime()),
"DHT t=" , str(DHT11_H) , "C| ",
"DHT r=", DHT11_R, "%| " ,
"BMP t=", BMP180_H, "C| " ,
"BMP p=", BMP180_P, "HPa"
)
#print (data)
time.sleep(10)
except usb.core.USBError:
print ("USB error")
except:
print ("write failed")
# end while
# This is needed to release interface, otherwise attach_kernel_driver fails
# due to "Resource busy"
usb.util.dispose_resources(dev)
# It may raise USBError if there's e.g. no kernel driver loaded at all
if reattach:
dev.attach_kernel_driver(0)