XR16C2850CM48 EXAR [Exar Corporation], XR16C2850CM48 Datasheet - Page 23

• Manufacturer Part Number: XR16C2850CM48
• Description: 3.3V AND 5V DUART WITH 128-BYTE FIFO
• Manufacturer: EXAR [Exar Corporation]

XR16C2850
REV. 2.0.0
FCR[3]: DMA Mode Select
Controls the behavior of the TXRDY# and RXRDY#
pins. See DMA operation section for details.
• Logic 0 = Normal Operation (default).
• Logic 1 = DMA Mode.
FCR[5:4]: Transmit FIFO Trigger Select
(logic 0 = default, TX trigger level = one)
These 2 bits set the trigger level for the transmit FIFO.
The UART will issue a transmit interrupt when the
number of characters in the FIFO falls below the se-
lected trigger level, or when it gets empty in case that
the FIFO did not get filled over the trigger level on last
re-load. Table 10 below shows the selections. EFR
bit-4 must be set to ‘1’ before these bits can be ac-
FCTR
B
IT
0
0
1
1
-5
FCTR
B
IT
0
1
0
1
-4
B
FCR
IT
X
0
0
1
1
0
0
1
1
0
0
1
1
T
-7
ABLE
B
FCR
10: T
IT
X
0
1
0
1
0
1
0
1
0
1
0
1
-6
3.3V AND 5V DUART WITH 128-BYTE FIFO
RANSMIT AND
B
FCR
IT
X
0
0
0
1
1
0
0
1
1
-5
BIT
FCR
X
0
0
1
0
1
0
1
0
1
-4
R
ECEIVE
T
Programmable
FCTR[7] = 0.
RIGGER
1 (default)
via TRG
R
register.
23
ECEIVE
FIFO T
14
16
24
28
16
56
60
4
8
8
8
cessed. Note that the receiver and the transmitter
cannot use different trigger tables. Whichever selec-
tion is made last applies to both the RX and TX side.
FCR[7:6]: Receive FIFO Trigger Select
(logic 0 = default, RX trigger level =1)
The FCTR Bits 5-4 are associated with these 2 bits.
These 2 bits are used to set the trigger level for the
receive FIFO. The UART will issue a receive interrupt
when the number of the characters in the FIFO cross-
es the trigger level. Table 10 shows the complete se-
lections.
N
trigger tables. Whichever selection is made last applies to
both the RX and TX side.
L
OTE
EVEL
: The receiver and the transmitter cannot use different
RIGGER
T
Programmable
FCTR[7] = 1.
RIGGER
1 (default)
T
register.
via TRG
RANSMIT
16
24
30
16
32
56
L
8
8
EVEL
L
EVEL
S
ELECTION
Table-A. 16C550, 16C2550,
16C2552, 16C554, 16C580
compatible.
Table-B. 16C650A compatible.
Table-C. 16C654 compatible.
Table-D. 16C850, 16L2752,
16L2750, 16C2852, 16C854,
16C864, 16C872 compatible.
C
OMPATIBILITY