XR88C681CP/28 EXAR [Exar Corporation], XR88C681CP/28 Datasheet - Page 79

• Manufacturer Part Number: XR88C681CP/28
• Description: CMOS Dual Channel UART (DUART)
• Manufacturer: EXAR [Exar Corporation]

H. SPECIAL MODES OF OPERATION
H.1 RTS/CTS Handshaking
The DUART can be programmed to support RTS/CTS
Handshaking, as a means of data flow control with other
devices. This section will describe a couple of options that
the DUART allows the user in implementing RTS/CTS
Handshaking. Specifically, these options are:
D Receiver-Controlled RTS/CTS Handshaking
D Transmitter-Controlled RTS/CTS Handshaking
Rev. 2.11
FFULLA
RXDA
RTSA
Figure 42. Block Diagram and Timing Sequence of Two DUARTs Connected
Receiving Device
To CPU
FFULLA
(OP4)
in the Receiver-RTS Controlled Configuration
RTSA
RXDA
CTSA
(OP0)
TXDA
(IP0)
79
H.1.1 Receiver-Controlled RTS/CTS Handshaking
In this mode, the Receiver has the ability to automatically
negate the RTS output (to the Transmitting device).
Specifically, this mode allows the Receiver to negate the
RTS signal if its RHR is full; and, is thereby, very effective
in preventing Receiver Overrun Errors.
presents a diagram of an example illustrating the
operation of the Receiver-Controlled RTS configuration.
CTSB
(IP1)
TXDB
RXDB
RTSB
(OP1)
Transmitting Device
XR88C681
Figure 42