hi there,
im trying to use the serialport connection between activities but i cant,
when the next activity appears reset all what the previous activity did

How a i can keep the connection

im desperate!
thnaks for reply

When compiling and installing the apk I can connect to the cdc device and I'm assuming the command gets sent, however, I am receiving no feedback.

This does work with DroidTerm though.

I'm running this on KitKat (4.4) if that helps.

Thank you.

I am trying to send AT commands from android app to adafruit fona, through usb OTG cable. When I type some AT command, nothing is really happening, but the USB serial terminal app from the play store is able to send AT command through USB.

When I try to read data, I receive abnormal text decoded. I tried many encoding but result is same.

I'm trying to send zeros to my arduino Uno with serialPort.write(new byte[0x00]), but nothing happens. With another program (Serial USB Terminal), it works properly.

    @Override
    public void handleMessage(Message msg) {
        switch (msg.what) {
            case UsbService.MESSAGE_FROM_SERIAL_PORT:
                String data = (String) msg.obj;
                mActivity.get().display.append(data);
                break;
        }
    }

I'm sending a request which consists of 3 or 8 bytes. In response, I have to get an array of the same 3 or 8 bytes. How do I do that? Send I got.
byte[] cats = {0x00, 0x05, 0x3F};
usbService.write(cats);
Here's how to accept and display, I do not know ...
Can you help me?
Sorry for my English.

I want to thank you for sharing UsbSerial and the SeirialPortExample.

I have a question about some logic in the findSerialPortDevice() routine of the SerialPortExample in the UsbService.java file.

in line 158 inside findSerialPortDevice():

if (deviceVID != 0x1d6b && (devicePID != 0x0001 || devicePID != 0x0002 || devicePID != 0x0003))

This will exclude all devices with a deviceVID of 0x1d6b without regard to the value of the devicePID because (devicePID != 0x0001 || devicePID != 0x0002 || devicePID != 0x0003) will be true for all values of devicePID.

is it possible you intended:

if ( !(deviceVID == 0x1d6b && (devicePID == 0x0001 || devicePID == 0x0002 || devicePID == 0x0003)))

I think this would only exclude a device if it both had a VID of 1d6b and a PID of 1,2 or 3 allowing all other PID's for that VID.

or did you intend something else?