user18795: I have a Arduino Pro Micro and use the USB port for programming. Is it possible to use the hardware serial port for connecting with a peripheral while I'm using the USB port (and hence the hardware serial port) for programming? Or must I disconnect the USB cable or otherwise reconfigure the hardware?

user6628: I have a Teensy 2.0 with a ATmega32u4 and I can use both, with the USB as Serial.* and the hardware UART as Serial1.* 
For the Arduino Pro Micro it is the same.  See Arduino Pro Micro, get data out of Tx pin?
For Teensy, see https://www.pjrc.com/teensy/td_uart.html 

18795: <p>I have a Arduino Pro Micro and use the USB port for programming. Is it possible to use the hardware serial port for connecting with a peripheral while I'm using the USB port (and hence the hardware serial port) for programming? Or must I disconnect the USB cable or otherwise reconfigure the hardware?</p>
 6628: <p>I have a Teensy 2.0 with a ATmega32u4 and I can use both, with the USB as Serial.* and the hardware UART as Serial1.* </p>

<p>For the Arduino Pro Micro it is the same.  See <a href="https://arduino.stackexchange.com/q/1471/6628">Arduino Pro Micro, get data out of Tx pin?</a></p>

<p>For Teensy, see <a href="https://www.pjrc.com/teensy/td_uart.html" rel="nofollow noreferrer">https://www.pjrc.com/teensy/td_uart.html</a> </p>
