UART communications require two pins: Receive Data (RX) and Transmit Data (TX):
- RX (Receive Data): The serial data input.
Oversampling techniques are used on the receive signal for accuracy of incoming
data.
- TX (Transmit Data): The serial data output. When
the transmitter is enabled and no data needs to be transmitted, the TX pin is
held high (idle). In some bidirectional protocols like ISO7816 Smart card, this
pin is also used to receive data.
In hardware flow control mode, the following pins are also used. Note that this functionatlity is only available in UNICOMM-UART instances that implement the UART-FLOW-CONTROL feature.
- CTS (Clear To Send): The flow control input. When
driven high by an external signal, this signal blocks the data transmission at
the end of the current transfer.
- RTS (Request To Send): The flow control output.
When held low, this signal indicates that the UART is ready to receive data.