Lost connection in USB switching

[chaitannya.mahatme]

We are using AD2 on custom design imx6 based microcontroller. 

The controller has only 2 USB ports & we are using a USB switching IC to switch between multiple devices. 

The device performs well as long as we are not switching the USB port, but when switching is performed the device stops collecting data. 

The USB switching action  is equivalent of disconnecting & reconnecting USB cable. We are using Python for our application. 

Here's the code. 

 

Quote

dwf.FDwfDeviceOpen(c_int(-1), byref(self.h))

.

.

# Switch USB port to AD2 interface.

dwf.FDwfAnalogInConfigure(self.h, c_bool(False), c_bool(True))  # activate oscilloscope

  for iTrigger in range(nAverage):
        # new acquisition is started automatically after done state 
            while True:
                dwf.FDwfAnalogInStatus(self.h, c_bool(True), byref(self.sts))
                # print(self.sts.value)
                # print(DwfStateDone.value)
                if self.sts.value == DwfStateDone.value:
                    break
                time.sleep(0.001)
            # define channel to receive data
            channel = c_int(self.nCH - 1)
            # pass data to vector
            dwf.FDwfAnalogInStatusData(self.h, channel, rxData, self.nRecLength)  # get channel 1 data

dwf.FDwfAnalogInConfigure(self.h, c_bool(False), c_bool(True))  # deactivate oscilloscope before USB switching.

# Switch USB port to different interface.

What can be the possible error. 

[attila]

Hi @chaitannya.mahatme

Disconnecting the USB channel will loose the software connection, so the data collection will stop. After reconnect it is required to "open" and configure the device again.

I would recommend using an USB hub instead of switch.