USART Flow control

The USART supports both hardware and software flow control.

Hardware flow control

The USART supports hardware flow control using RTS and/or CTS signalling. If RTS is configured to appear on a device pin so that it can be sent to an external device, it indicates to an external device the ability of the receiver to receive more data.

If connected to a pin, and if enabled to do so, the CTS input can allow an external device to throttle the USART transmitter.

c-Flowcontrol.html#d15e2125__BEHIHFAG shows an overview of RTS and CTS within the USART.

Hardware flow control using RTS and CTS

Software flow control

Software flow control could include XON / XOFF flow control, or other mechanisms. these are supported by the ability to check the current state of the CTS input, and/or have an interrupt when CTS changes state (via the CTS and DELTACTS bits, respectively, in the STAT register), and by the ability of software to gracefully turn off the transmitter (via the TXDIS bit in the CTL register).