FDC37C669 Datasheet, PDF (82/164 Pages) SMSC Corporation – PC 98/99 COMPLIANT SUPER I/O FLOPPY DISK CONTROLLER WITH INFRARED SUPPORT

XMITTER are controlled separately, either one
or both can be in the polled mode of operation.
In this mode, the user's program will check
RCVR and XMITTER status via the LSR. LSR
definitions for the FIFO Polled Mode are as
follows:
- Bit 0=1 as long as there is one byte in the
RCVR FIFO.
- Bits 1 to 4 specify which error(s) have
occurred. Character error status is handled
the same way as when in the interrupt
mode, the IIR is not affected since EIR bit
2=0.
- Bit 5 indicates when the XMIT FIFO is
empty.
- Bit 6 indicates that both the XMIT FIFO and
shift register are empty.
- Bit 7 indicates whether there are any errors
in the RCVR FIFO.
There is no trigger level reached or timeout
condition indicated in the FIFO Polled Mode,
however, the RCVR and XMIT FIFOs are still
fully capable of holding characters.
DESIRED
BAUD RATE
50
75
110
134.5
150
300
600
1200
1800
2000
2400
3600
4800
7200
9600
19200
38400
57600
115200
230400
460800
Table 33 - Baud Rates Using 1.8462 MHz Clock (24 MHz/13)
DIVISOR USED TO
PERCENT ERROR DIFFERENCE
GENERATE 16X CLOCK BETWEEN DESIRED AND ACTUAL*
2307
0.03
1538
0.03
1049
0.005
858
0.01
769
0.03
384
0.16
192
0.16
96
0.16
64
0.16
58
0.5
48
0.16
32
0.16
24
0.16
16
0.16
12
0.16
6
0.16
3
0.16
2
1.6
1
0.16
32770
0.16
32769
0.16
CROC:
BIT 7 OR 6
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
1
1
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