XR21V1412 Datasheet, PDF (9/24 Pages) Exar Corporation – 2-CH FULL-SPEED USB UART

XR21V1412
REV. 1.0.0
2-CH FULL-SPEED USB UART
prevent data overrun to the remote RX FIFO. The CTS# input is monitored to suspend/restart the local
transmitter (see Figure 3):
FIGURE 3. AUTO RTS AND CTS FLOW CONTROL OPERATION
Local UART
UARTA
Receiver FIFO
RXA
Trigger Reached
Remote UART
UARTB
TXB
Transmitter
Auto RTS
Trigger Level
Transmitter
RTSA#
TXA
CTSB#
RXB
Auto CTS
Monitor
Receiver FIFO
Trigger Reached
Auto CTS
Monitor
CTSA#
RTSA#
CTSB#
TXB
Assert RTS# to Begin
Transmission
1
ON
2
ON
3
Data Starts
4
RXA FIFO
Receive
INTA
(RXA FIFO
Data ^{RX FIFO}
5
Trigger Level
Interrupt)
RTSB#
Auto RTS
Trigger Level
OFF
7
8 ^OFF
10 ON
11
ON
6 _Suspend
Restart
9
RTS High
Threshold
RTS Low
Threshold
RX FIFO
12 _{Trigger Level}
RTSCTS1
9