I have only the 4 pin USB TTL cable which has the Rx, Tx, Vcc and GND pins. The 6 pin includes the CTS and RTS pins also, and is specified for use with Intel Galileo board. My question is if I can still use it for normal serial data communications and what will be the difference?

Cable specifics mentioned here: https://www.intel.com/content/www/us/en/support/boards-and-kits/intel-galileo-boards/000006343.html


2 Answers 2


CTS and RTS are for flow signaling (Clear To Send) and (Request To Send). If you want to use 4 pins and you find out nothing is flowing through, you may want to pull CTS down to GND.

In one post OP claimed I have the Arduinos communicating properly without these pins in use.. There OP had Arduinos communicating, they at least can survive without flow control.


You can

  • program the UART to not use handshaking,
  • or even use software handshaking.
  • or connect them permanently to GND.

But for high speed and reliable communication, its best to use the handshaking lines.

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