xr16m681 Exar Corporation, xr16m681 Datasheet - Page 16

• Manufacturer Part Number: xr16m681
• Description: 1.62v To 3.63v Uart With 32-byte Fifo And Vlio Interface
• Manufacturer: Exar Corporation

XR16M681
1.62V TO 3.63V UART WITH 32-BYTE FIFO AND VLIO INTERFACE
Automatic RTS hardware flow control is used to prevent data overrun to the local receiver FIFO. The RTS#
output is used to request remote unit to suspend/resume data transmission. The auto RTS flow control
features is enabled to fit specific application requirement (see
•
•
If using the Auto RTS interrupt:
•
With the Auto RTS function enabled, an interrupt is generated when the receive FIFO reaches the selected RX
trigger level. The RTS# pin will not be forced HIGH (RTS off) until the receive FIFO reaches one trigger level
above the selected trigger level in the trigger table
is unloaded to one level below the selected trigger level. Under the above described conditions, the M681 will
continue to accept data until the receive FIFO gets full. The Auto RTS function is initiated when the RTS#
output pin is asserted LOW (RTS On).
Automatic CTS flow control is used to prevent data overrun to the remote receiver FIFO. The CTS# input is
monitored to suspend/restart the local transmitter. The auto CTS flow control feature is selected to fit specific
application requirement (see
•
If needed, the CTS interrupt can be enabled through IER bit-7 (after setting EFR bit-4). The UART issues an
interrupt when the CTS# pin is de-asserted (HIGH): ISR bit-5 will be set to 1, and UART will suspend
2.10
2.11
2.12
Enable auto RTS flow control using EFR bit-6.
The auto RTS function must be started by asserting RTS# output pin (MCR bit-1 to logic 1 after it is enabled).
Enable RTS interrupt through IER bit-6 (after setting EFR bit-4). The UART issues an interrupt when the
RTS# pin makes a transition from low to high: ISR bit-5 will be set to logic 1.
Enable auto CTS flow control using EFR bit-7.
R
X
Auto RTS (Hardware) Flow Control
Auto RTS Hysteresis
Auto CTS Flow Control
T
RIGGER
16
24
28
8
L
EVEL
Figure
T
ABLE
INT P
12):
4: A
IN
A
16
24
28
8
UTO
CTIVATION
RTS (H
(Table
ARDWARE
16
RTS# D
(C
9). The RTS# pin will return LOW after the RX FIFO
HARACTERS IN
Figure
) F
E
-
LOW
ASSERTED
16
24
28
28
12):
C
ONTROL
R
X
(H
F
IFO
IGH
)
)
(C
RTS# A
HARACTERS IN
SSERTED
16
24
0
8
R
REV. 1.0.0
(L
X
F
OW
IFO
)
)