xr16m890 Exar Corporation, xr16m890 Datasheet - Page 20

• Manufacturer Part Number: xr16m890
• Description: Uart With 128-byte Fifo And Integrated Level Shifters
• Manufacturer: Exar Corporation

XR16M890
UART WITH 128-BYTE FIFO AND INTEGRATED LEVEL SHIFTERS
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 M890 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).
selected.
1.11
1.12
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.
R
X
Auto RTS (Hardware) Flow Control
Auto RTS Hysteresis
T
RIGGER
16
56
60
8
L
EVEL
T
ABLE
INT P
4: A
IN
A
16
56
60
8
Table 4
UTO
CTIVATION
RTS (H
PRELIMINARY
below explains this when the Trigger Table-C
(Table
ARDWARE
20
RTS# D
(C
10). The RTS# pin will return LOW after the RX FIFO
HARACTERS IN
Figure
) F
E
-
LOW
ASSERTED
16
56
60
60
15):
C
ONTROL
R
X
(H
F
IFO
IGH
)
)
(C
RTS# A
HARACTERS IN
SSERTED
16
56
0
8
(Table
REV. P1.1.1
R
(L
X
F
OW
10) is
IFO
)
)