public void stop() {
        if(mState.compareAndSet(State.RUNNING, State.STOPPING)) {
            synchronized (mWriteBufferLock) {
                mWriteBufferLock.notifyAll(); // wake up write thread to check the stop condition
            }
            Log.i(TAG, "Stop requested");
        }
    }
stop SerialInputOutputManager threads

when using readTimeout == 0 (default), additionally use usbSerialPort.close() to
interrupt blocking read
usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/util/SerialInputOutputManager.java