XR16C2850IJ EXAR [Exar Corporation], XR16C2850IJ Datasheet - Page 27

• Manufacturer Part Number: XR16C2850IJ
• Description: 2.97V TO 5.5V DUAL UART WITH 128-BYTE FIFOS
• Manufacturer: EXAR [Exar Corporation]

xr
REV. 2.1.3
FCR[3]: DMA Mode Select
Controls the behavior of the TXRDY# and RXRDY# pins. See DMA operation section for details.
•
•
FCR[5:4]: Transmit FIFO Trigger Select
(logic 0 = default, TX trigger level = 1)
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 selected trigger level, or when it gets empty in case that the
FIFO did not get filled over the trigger level on last re-load.
must be set to ‘1’ before these bits can be accessed. Note that the receiver and the transmitter cannot use
different trigger tables. Whichever selection 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 crosses the
trigger level.
different trigger tables. Whichever selection is made last applies to both the RX and TX side.
Logic 0 = Normal Operation (default).
Logic 1 = DMA Mode.
T
Table-C
Table-D
Table-A
Table-B
RIGGER
T
ABLE
FCTR
Table 10
B
IT
0
0
1
1
T
-5
ABLE
FCTR
B
10: T
IT
shows the complete selections. Note that the receiver and the transmitter cannot use
0
1
0
1
-4
RANSMIT AND
B
FCR
IT
X
0
0
1
1
0
0
1
1
0
0
1
1
-7
B
FCR
IT
0
1
0
1
0
1
0
1
0
1
0
1
X
-6
R
ECEIVE
B
FCR
IT
X
0
0
0
1
1
0
0
1
1
-5
FIFO T
27
BIT
FCR
2.97V TO 5.5V DUAL UART WITH 128-BYTE FIFOS
X
0
0
1
0
1
0
1
0
1
-4
RIGGER
Table 10
T
Programmable
FCTR[7] = 0.
RIGGER
1 (default)
R
via TRG
register.
T
ECEIVE
ABLE AND
14
16
24
28
16
56
60
4
8
8
8
L
below shows the selections. EFR bit-4
EVEL
L
Programmable
FCTR[7] = 1.
EVEL
1 (default)
T
T
register.
via TRG
RANSMIT
L
RIGGER
EVEL
16
24
30
16
32
56
8
8
S
ELECTION
16C550, 16C2550,
16C2552, 16C554,
16C580
16C650A
16C654
16L2752, 16L2750,
16C2852, 16C850,
16C854, 16C864
C
OMPATIBILITY
XR16C2850