Serial communication
Flow control
Digi XBee® 3 802.15.4 RF Module User Guide
82
RTS flow control
If you set
to enable RTS flow control, the device does not send data in
the serial transmit buffer out the DOUT pin as long as RTS is de-asserted (set high). Do not de-assert
RTS for long periods of time or the serial transmit buffer will fill. If the device receives an RF data
packet and the serial transmit buffer does not have enough space for all of the data bytes, it discards
the entire RF data packet.
If the device sends data out the UART when RTS is de-asserted (set high) the device could send up to
five characters out the UART port after RTS is de-asserted.
Cases in which the DO buffer may become full, resulting in dropped RF packets:
1. If the RF data rate is set higher than the interface data rate of the device, the device may
receive data faster than it can send the data to the host. Even occasional transmissions from a
large number of devices can quickly accumulate and overflow the transmit buffer.
2. If the host does not allow the device to transmit data out from the serial transmit buffer due to
being held off by hardware flow control.
