XR16L784 Exar Corporation, XR16L784 Datasheet - Page 25

• Manufacturer Part Number: XR16L784
• Description: High Performance 5V And 3.3V Quad Uart
• Manufacturer: Exar Corporation

Logic 0 = No transmit FIFO reset. (default)
Logic 1 = Reset the transmit FIFO pointers and FIFO
level counter logic (the transmit shift register is not
cleared or altered). This bit will return to a logic 0 after
resetting the FIFO.
FCR[3]: DMA Mode Select
This bit has no effect since TXRDY and RXRDY pins
are not available in this device. It is provided for lega-
cy software.
Logic 0 = Set DMA to mode 0. (default)
Logic 1 = Set DMA to mode 1.
FCR[5:4]: Transmit FIFO Trigger Select
(logic 0 = default, TX trigger level = one)
The Line Control Register is used to specify the asyn-
chronous data communication format. The word or
character length, the number of stop bits, and the
parity are selected by writing the appropriate bits in
this register.
4.11.4 Line Control Register (LCR)
FCTR
B
IT
0
0
1
1
-7
FCTR
B
IT
0
1
0
1
-6
B
FCR
IT
X
0
0
1
1
0
0
1
1
0
0
1
1
T
-7
ABLE
B
FCR
10: T
IT
0
1
0
1
0
1
0
1
0
1
0
1
X
-6
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 Programmable Table-D. 16C850, 16c2850,
RIGGER
1 (default)
R
ECEIVE
25
14
16
24
28
16
56
60
FIFO T
4
8
8
8
The FCTR Bits 6-7 are associated with these 2 bits
by selecting one of the four tables. The 4 user select-
able trigger levels in 4 tables are supported for com-
patibility reasons. These 2 bits set the trigger level for
the transmit FIFO interrupt. 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.
low shows the selections.
FCR[7:6]: Receive FIFO Trigger Select
(logic 0 = default, RX trigger level =1)
The FCTR Bits 6-7 are associated with these 2 bits.
These 2 bits are used to set the trigger level for the
receiver FIFO interrupt.
selections.
LCR[1-0]: TX and RX Word Length Select
These two bits specify the word length to be transmit-
ted or received.
HIGH PERFORMANCE 5V AND 3.3V QUAD UART
L
EVEL
RIGGER
T
RIGGER
1 (default)
T
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.
16C2852, 16C854, 16C864,
16C872 compatible.
Table 10
C
OMPATIBILITY
shows the complete
XR16L784
Table 10
REV. 1.0.1
be-