
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. 
SMSC DS – LPC47M192 
Page 73 
Rev. 03/30/05 
DATASHEET 
FIFO POLLED MODE OPERATION 
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. 
Table 30  - Baud Rates 
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 
DIVISOR USED TO 
GENERATE 16X CLOCK
2304 
1536 
1047 
857 
768 
384 
192 
96 
64 
58 
48 
32 
24 
16 
12 
6 
3 
2 
1 
32770 
32769 
PERCENT ERROR DIFFERENCE 
BETWEEN DESIRED AND ACTUAL
1
0.001 
- 
- 
0.004 
- 
- 
- 
- 
- 
0.005 
- 
- 
- 
- 
- 
- 
0.030 
0.16 
0.16 
0.16 
0.16 
HIGH 
SPEED BIT
2
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
1 
1 
Note
1
:  The percentage error for all baud rates, except where indicated otherwise, is 0.2%. 
Note
2
: The High Speed bit is located in the Device Configuration Space. 
Table 31 - Reset Function Table 
REGISTER/SIGNAL
RESET CONTROL 
RESET STATE
Interrupt Enable Register 
RESET 
All bits low 
Interrupt Identification Reg. 
RESET 
Bit 0 is high; Bits 1 - 7 low 
FIFO Control 
RESET 
All bits low 
Line Control Reg. 
RESET 
All bits low 
MODEM Control Reg. 
RESET 
All bits low 
Line Status Reg. 
RESET 
All bits low except 5, 6 high 
MODEM Status Reg. 
RESET 
Bits 0 - 3 low; Bits 4 - 7 input