LPC47S457-NC SMSC [SMSC Corporation], LPC47S457-NC Datasheet - Page 71

• Manufacturer Part Number: LPC47S457-NC
• Description: Advanced I/O with X-Bus Interface
• Manufacturer: SMSC [SMSC Corporation]

Character timeout and RCVR FIFO trigger level interrupts have the same priority as the current received data available
interrupt; XMIT FIFO empty has the same priority as the current transmitter holding register empty interrupt.
6.5.5
With FCR bit 0 = "1" resetting IER bits 0, 1, 2 or 3 or all to zero puts the UART in the FIFO Polled Mode of operation.
Since the RCVR and 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.
Note
Note
SMSC DS – LPC47S45x
1
2
: The percentage error for all baud rates, except where indicated otherwise, is 0.2%.
: The High Speed bit is located in the Device Configuration Space.
FIFO POLLED MODE OPERTION
BAUD RATE
DESIRED
115200
230400
460800
19200
38400
57600
134.5
1200
1800
2000
2400
3600
4800
7200
9600
110
150
300
600
50
75
GENERATE 16X CLOCK
DIVISOR USED TO
32770
32769
2304
1536
1047
857
768
384
192
96
64
58
48
32
24
16
12
6
3
2
1
DATASHEET
Table 30 − Baud Rates
Page 71 of 259
BETWEEN DESIRED AND ACTUAL
PERCENT ERROR DIFFERENCE
0.001
0.004
0.005
0.030
0.16
0.16
0.16
0.16
-
-
-
-
-
-
-
-
-
-
-
-
-
1
SPEED BIT
HIGH
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
1
1
Rev. 07/09/2001
2