Read from USB after write to USB

Projects Interfacing w/ Software on the Computer
1

Hi,

I have connected Arduino to Raspberry Pi and I need read response from USB after send command, but I have problem.

Python code:

#!/usr/bin/python
from __future__ import print_function

###############################
#     BeagleBoard
# Decimal VendorID=6790 & ProductID=29987
# Hexadecimal VendorID=0x1a86 & ProductID=0x7523
###############################

import sys
import usb.core
import usb.util

ard = None
arddev = None
ardendpoint= None

def ArduinoConect():
  global ard
  global arddev
  global ardendpoint

  try:
    #device = usb.core.find(idVendor=0x0483, idProduct=0x5750)
    arddev = usb.core.find(idVendor=0x1a86, idProduct=0x7523)
    # was it found?
    if arddev is None:
      print("Arduino Error")
    else:
      print("Gotowy")

      #raise ValueError('Device not found')
      c = 1
      for config in arddev:
        for i in range(config.bNumInterfaces):
          if arddev.is_kernel_driver_active(i):
            arddev.detach_kernel_driver(i)
          #print i
        c+=1
      # use the first/default configuration
      arddev.set_configuration()

      # first endpoint
      ardendpoint = arddev[0][(0,0)][0]

      # read a data packet
      data = None

      # get an endpoint instance
      cfg = arddev.get_active_configuration()
      intf = cfg[(0,0)]
      ard = 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 ard is not None
      # write the data
      #ard.write('0')
  except ValueError:
    print("blad sprawdzenia")


ArduinoConect();

while 1:
  val=raw_input("comenda: ");
  ard.write(val + "\r\n")


  # read a data packet
  #print arddev
  try:
    data = arddev.read(ardendpoint.bEndpointAddress,ardendpoint.wMaxPacketSize)
    RxData = ''.join([chr(x) for x in data])
    print(RxData)
  except usb.core.USBError as e:
    data = None
    print( e.args)

I get result:

root@beaglebone:/home/debian/budka# ./arduino-test.py
Gotowy
comenda: 2
(110, u'Operation timed out')
comenda: 2
(110, u'Operation timed out')
comenda: 1
(110, u'Operation timed out')
comenda: 1
LED_OFF
LED_OFF
LED_ON
LED_ON
comenda: 1
(110, u'Operation timed out')
comenda: 1
(110, u'Operation timed out')
comenda: 1
(110, u'Operation timed out')
comenda: 2

LED_ON
LED_ON
LED_ON
LED_OF
comenda:

Respons should be after each command, but not working.
Any ideas?

Thanks
Dario

2

(deleted)

3

Why are you not using pySerial ?

This Python - Arduino demo may be of interest.

I was recently fiddling around with direct writing to a USB device with Python. I believe a USB device has separate endpoints for sending and receiving.

...R

4

Hello, raczkowski1!
I have the same problem. Did you find any solution?
I have arduino micro, connected to my PC with Windows10. And 2 programms: Arduino IDE and Hercules.
I'm trying to send request from Hercules (on my PC) to arduino via USB (virtual COM). Arduino gets this request, understand it, but doesn't answer to my PC. It happens from arduino's power on till connecting arduino to Arduino IDE serial port monitor. After that it works properly with my program, with Arduino's monitor, but doesn't answer to Hercules.

5

I found the solution!
The problem was with uninstalled DTR and RTS! Not properly flow control. Thanks to jensdewispelaere: Arduino not sending usb serial data - Storage - Arduino Forum