XR16L788 Exar Corporation, XR16L788 Datasheet - Page 14

• Manufacturer Part Number: XR16L788
• Description: High-performance 3.3V Octal Uart
• Manufacturer: Exar Corporation

Programming the Baud Rate Generator Registers
DLM and DLL provides the capability of selecting the
operating data rate.
rates available with a 14.7456 MHz crystal or external
clock at 16X clock rate. At 8X sampling rate, these
T
Automatic RTS/DTR flow control is used to prevent
data overrun to the local receiver FIFO. The RTS#/
DTR# output pin is used to request remote unit to
suspend/resume data transmission. The flow control
features are individually selected to fit specific appli-
cation requirement (see Figure 8):
O
4.2 A
ABLE
UTPUT
MCR Bit-7=1
divisor (decimal) = (XTAL1 clock frequency / prescaler) / (serial data rate x 16),
divisor (decimal) = (XTAL1 clock frequency / prescaler) / (serial data rate x 8),
230.4k
TROL
115.2k
6: T
19.2k
38.4k
57.6k
1200
2400
4800
9600
100
600
UTOMATIC
Data Rate
YPICAL DATA RATES WITH A
O
F
PERATION
IGURE
XT A L1
XT A L2
RTS/DTR H
O
UTPUT
Table 6
7. B
MCR Bit-7=0
153.6k
230.4k
460.8k
921.6k
19.2k
38.4k
76.8k
2400
4800
9600
400
AUD
Data Rate
shows the standard data
ARDWARE
C rystal
R
Buffer
O sc/
ATE
G
C hannels
T o O ther
Clock (Decimal)
D
14.7456 MH
ENERATOR
IVISOR FOR
F
LOW
2304
384
192
96
48
24
12
6
4
2
1
D ivide by 4
D ivide by 1
Prescaler
Prescaler
C
ON
16x
Z CRYSTAL OR EXTERNAL CLOCK AT
-
D
14
IVISOR FOR
Clock (HEX)
data rates would double. When using a non-standard
data rate crystal or external clock, the divisor value
can be calculated for channel ‘N’ with the following
equation(s).
- Select RTS (and CTS) or DTR (and DSR) through
- Enable auto RTS/DTR flow control using EFR bit-6.
- The auto RTS/DTR function must be started by as-
M C R Bit-7=0
M C R Bit-7=1
MCR bit-2.
serting RTS/DTR# output pin (MCR bit-0 or 1 to
logic 1 after it is enabled.
900
180
C0
0C
(default)
60
30
18
06
04
02
01
16x
Baud R ate
D LL and D LM
G enerator
R egisters
Logic
DLM P
V
ALUE
09
01
00
00
00
00
00
00
00
00
00
ROGRAM
(HEX)
WHEN
WHEN
XR16L788 OCTAL UART
R ate C lock to
and R eceiver
8XMODE-
8XMODE-
T ransm itter
DLL P
16X or 8X
Sam pling
16X S
V
ALUE
C0
0C
00
80
60
30
18
06
04
02
01
ROGRAM
AMPLING
(HEX)
BIT
BIT
N
N
IS
IS
D
E
0
1
ATA
REV. 1.1.4
RROR
0
0
0
0
0
0
0
0
0
0
0
R
ATE
(%)