CP21xx driver, does not work on it's own when there are multiple interfaces/ports

[ameyav21]

So far it worked fine and there were no issues with FTDI. Now, I’m trying to work with a device which uses CP21xx driver which has two ports - “standard” and “enhanced”, my messages work on “standard” and I have changed the part of code in Android/drivers/CP21xx…cs to set the interface to the one with “Standard”, but my messages don’t get a response from the device.

Now, if I use a 3rd party app “Serial usb terminal” https://play.google.com/store/apps/details?id=de.kai_morich.serial_usb_terminal&hl=en_CA&gl=US

, whose source code I don’t have,and thensend my messages, get the reply from the device, and then use the UsbSerialForAndroid example app again, I now get responses to all my messages.

I tried setting it to always the "standard" interface by checking the name but that still doesn't work unless I use the third party app. I have also tried using a usb to ttl to see what the third party app sends as a message and what my app sends and they are identical.

Note that the code or configuration doesn’t change for the UsbSerialForAndroid. Also, once working, even if I close the app or send messages after a very long time , I still get replies, till the time I don’t remove the physical usb connection.

If I unplug and reply the usb or power cycle the device that uses the CP21x driver, then I again have to use the third party app first to get the UsbSerialForAndroid sample app working again. I don’t know why it needs that third party app to connect and send the messages first although I don’t change anything in the UsbSerialForAndroid app between those two scenarios.

this is the open function for the cp21xx driver, I edited it to not use enhanced port

public override void Open(UsbDeviceConnection connection)
{
if (mConnection != null)
{
throw new IOException("Already opened.");
}

mConnection = connection;
Boolean opened = false;
try
{
    for (int i = 0; i < mDevice.InterfaceCount; i++)
    {
        UsbInterface usbIface = mDevice.GetInterface(i);
        if (mConnection.ClaimInterface(usbIface, true))
        {
            Log.Debug(TAG, $"claimInterface {i} SUCCESS");
        }
        else
        {
            Log.Debug(TAG, $"claimInterface {i} FAIL");
        }
    }

    UsbInterface dataIface = mDevice.GetInterface(mDevice.InterfaceCount - 1);
    if (dataIface.Name.Contains("Enhanced"))
    {
        dataIface = mDevice.GetInterface(mDevice.InterfaceCount - 2); ;
    }
    for (int i = 0; i < dataIface.EndpointCount; i++)
    {
        UsbEndpoint ep = dataIface.GetEndpoint(i);
        if (ep.Type == (UsbAddressing)UsbSupport.UsbEndpointXferBulk)
        {
            if (ep.Direction == (UsbAddressing)UsbSupport.UsbDirIn)
            {
                mReadEndpoint = ep;
            }
            else
            {
                mWriteEndpoint = ep;
            }
        }
    }

    SetConfigSingle(SILABSER_IFC_ENABLE_REQUEST_CODE, UART_ENABLE);
    SetConfigSingle(SILABSER_SET_MHS_REQUEST_CODE, MCR_ALL | CONTROL_WRITE_DTR | CONTROL_WRITE_RTS);
    SetConfigSingle(SILABSER_SET_BAUDDIV_REQUEST_CODE, BAUD_RATE_GEN_FREQ / DEFAULT_BAUD_RATE);
    //            setParameters(DEFAULT_BAUD_RATE, DEFAULT_DATA_BITS, DEFAULT_STOP_BITS, DEFAULT_PARITY);
    opened = true;
}
finally
{
    if (!opened)
    {
        try
        {
            Close();
        }
        catch (IOException e)
        {
            // Ignore IOExceptions during close()
        }
    }
}

}

I don't know if there's anywhere else to set it to one of two interfaces in the UsbSerialForAndroid "UsbSerialForAndroid" app.

Has anyone ever worked with CP21xx drivers that have multiple ports/ interfaces with Android and usb serial ? Or anything similar that has two ports/ interfaces ?

looking for how to work with xamarin android usb serial to work with a port driver having two interfaces/ ports