XR17C158 Exar Corporation, XR17C158 Datasheet - Page 38

• Manufacturer Part Number: XR17C158
• Description: Eight-channel Pci-based (UART)
• Manufacturer: Exar Corporation

PRELIMINARY
SCRATCH PAD REGISTER (SPR)
This is a 8-bit general purpose register for the user to
store temporary data. The content of this register is
preserved during sleep mode but becomes 0xFF (de-
fault) after a reset or a power off-on cycle.
This register controls the UART enhanced functions
that are not available on ST16C554 or ST16C654.
FEATURE CONTROL REGISTER (FCTR)
T
ABLE
T
ABLE
15: A
FCTR B
16: 16 S
UTO
0
0
0
0
0
0
MSR[7]
IT
RS485 H
0
0
0
0
0
9
0
0
1
1
1
1
1
1
1
1
-3 FCTR B
ELECTABLE
MSR[6]
ALF
0
0
0
0
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
IT
-
-2 FCTR B
DUPLEX
H
YSTERESIS
MSR[5]
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
D
0
0
1
1
0
0
IRECTION
IT
-1 FCTR B
L
MSR[4]
EVELS
38
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
FCTR [3:0] - Auto RTS/DTR Flow Control Hystere-
sis Select
These bits select the auto RTS/DTR flow control hys-
teresis and only valid when TX and RX Trigger Table-
D is selected (FCTR bit-6 and 7 are set to logic 1).
The RTS/DTR hysteresis is referenced to the RX
FIFO trigger level. After reset, these bits are set to
logic 0 selecting the next FIFO trigger level for hard-
ware flow control.
lectable hysteresis levels.
C
ONTROL
0
1
0
1
0
1
W
IT
HEN
-0
D
ELAY IN
T
D
PCI BUS OCTAL UART
RIGGER
ELAY FROM
RTS/DTR H
D
(
ATA
CHARACTERS
10
12
13
14
15
11
0
1
2
3
4
5
6
7
8
9
T
Table 16
ABLE
+/- 16
B
+/- 4
+/- 6
+/- 8
+/- 8
IT
0
T
(
YSTERESIS
S
RANSMIT
-D
) T
IME
IS
below shows the 16 se-
)
S
ELECTED
-
TO
-R
ECEIVE
XR17C158
REV. 1.0.0