K60P100M100SF2RM Datasheet, PDF (1563/1809 Pages) Freescale Semiconductor, Inc – K60 Sub-Family Reference Manual

Chapter 51 Universal Asynchronous Receiver/Transmitter (UART)
committed to prior to the dataword being fully received. While the NACK is being
received it is possible that the application code will read the data buffer such that
sufficient room will be made to store the dataword that is being NACKed. Even if room
has been made in the data buffer once the transmission of a NACK is completed, the
received data will always be discarded as a result of an overflow and the
ET7816[RXTHRESHOLD] value will be incremented by one. However, if sufficient
space now exists to write the received data which was NACK'ed the S1[OR] flag will be
blocked and kept from asserting.
51.8.6 Match address registers
The two match address registers allow a second match address function for a broadcast or
general call address to the serial bus, as an example.
51.8.7 Modem feature
This section describes the modem features.
51.8.7.1 Ready-to-receive using RTS
To help to stop overrun of the receiver data buffer, the RTS signal can be used by the
receiver to indicate to another UART that it is ready to receive data. The other UART can
send the data when its CTS signal is asserted. This handshaking conforms to the
TIA-232-E standard. A transceiver is necessary if the required voltage levels of the
communication link do not match the voltage levels of the UART's RTS and CTS signals.
UART
TRANSMITTER
TXD
CTS_B
RXD
RTS_B
UART
RECEIVER
RECEIVER
RXD
RTS_B
TXD
CTS_B
TRANSMITTER
Figure 51-214. Ready-to-receive
The transmitter's CTS signal can be used for hardware flow control whether its RTS
signal is used for hardware flow control, transceiver driver enable, or not at all.
K60 Sub-Family Reference Manual, Rev. 6, Nov 2011
Freescale Semiconductor, Inc.
1563