This library https://github.com/i-am-bigmike/HardwareSerial_flow_control allows CTS/RTS hardware handshake. You can keep on using same syntax or use the new extended Serialx.begin() syntax. It's a drop-in substitute for serial library you can found in Arduino, nothing to wrap or change. You have only to use one pin which is capable of Interrupt for serial input.
Last edited: