xr16c850im Exar Corporation, xr16c850im Datasheet - Page 18

• Manufacturer Part Number: xr16c850im
• Description: Uart With 128-byte Fifos And Infrared Irda Encoder/decoder
• Manufacturer: Exar Corporation

XR16C850
2.97V TO 5.5V UART WITH 128-BYTE FIFO
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
•
•
•
The 850 has a new feature that provides flow control trigger hysteresis while it maintains compatibility to
16C650A and 16C550. With the Auto RTS function enabled, an interrupt is generated when the receive FIFO
reaches the programmed RX trigger level. The RTS# pin will not be forced to a logic 1 (RTS off), until the
receive FIFO reaches the upper limit of the hysteresis level. The RTS# pin will return to a logic 0 after the RX
FIFO is unloaded to the lower limit of the hysteresis level. Under the above described conditions, the 850 will
continue to accept data until the receive FIFO gets full. The Auto RTS function is initiated when the RTS#
output pin is asserted to a logic 0 (RTS On). For complete details, see
2.14
2.15
T
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.
RIGGER
(Programmable)
Trigger Table-C
Trigger Table-D
(S
Trigger Table-A
Trigger Table-B
EE
Auto RTS (Hardware) Flow Control
Auto RTS Hysteresis
T
ABLE
T
ABLE
S
ELECTED
10)
FCTR
B
IT
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
-1
FCTR
B
IT
0
0
0
0
0
0
0
0
0
0
0
0
1
0
1
-0
T
ABLE
T
(C
RIGGER
HARACTERS
5: A
14
16
24
28
16
56
60
N
N
N
1
4
8
8
8
L
EVEL
UTO
)
18
RTS H
(C
H
HARACTERS
YSTERESIS
RTS
±4
±6
±8
YSTERESIS
-
-
-
-
-
-
-
-
-
-
-
-
Figure
)
13):
A
Table
CTIVATION
INT P
14
16
24
28
16
56
60
N
N
N
1
4
8
8
8
IN
5.
(C
D
E
HARACTERS
-A
RTS#
N + 4
N + 6
N + 8
SSERTED
14
14
16
24
28
28
16
56
60
60
4
8
xr
)
(C
A
HARACTERS
SSERTED
RTS#
REV. 2.3.1
N - 4
N - 6
N - 8
16
24
16
56
0
1
4
8
0
8
0
8
)