Advanced I/O Controller with Motherboard GLUE Logic
Datasheet
Bit 4
This bit is the complement of the Clear To Send (nCTS) input. If bit 4 of the MCR is set to logic “1”, this bit
is equivalent to nRTS in the MCR.
Bit 5
This bit is the complement of the Data Set Ready (nDSR) input. If bit 4 of the MCR is set to logic “1”, this
bit is equivalent to DTR in the MCR.
Bit 6
This bit is the complement of the Ring Indicator (nRI) input. If bit 4 of the MCR is set to logic “1”, this bit is
equivalent to OUT1 in the MCR.
Bit 7
This bit is the complement of the Data Carrier Detect (nDCD) input. If bit 4 of the MCR is set to logic “1”,
this bit is equivalent to OUT2 in the MCR.
6.28.11 SCRATCHPAD REGISTER (SCR)
Address Offset =7H, DLAB =X, READ/WRITE
This 8 bit read/write register has no effect on the operation of the Serial Port. It is intended as a
scratchpad register to be used by the programmer to hold data temporarily.
6.29 Programmable Baud Rate Generator (And Divisor Latches DLH,
DLL)
The Serial Port contains a programmable Baud Rate Generator that is capable of dividing the internal PLL
clock by any divisor from 1 to 65535. The internal PLL clock is divided down to generate a 1.8462MHz
frequency for Baud Rates less than 38.4k, a 1.8432MHz frequency for 115.2k, a 3.6864MHz frequency for
230.4k and a 7.3728MHz frequency for 460.8k. This output frequency of the Baud Rate Generator is 16x
the Baud rate. Two 8 bit latches store the divisor in 16 bit binary format. These Divisor Latches must be
loaded during initialization in order to insure desired operation of the Baud Rate Generator. Upon loading
either of the Divisor Latches, a 16 bit Baud counter is immediately loaded. This prevents long counts on
initial load. If a 0 is loaded into the BRG registers the output divides the clock by the number 3. If a 1 is
loaded the output is the inverse of the input oscillator. If a two is loaded the output is a divide by 2 signal
with a 50% duty cycle. If a 3 or greater is loaded the output is low for 2 bits and high for the remainder of
the count. The input clock to the BRG is a 1.8462 MHz clock. Table 6.30 shows the baud rates possible.
6.29.1 Effect Of The Reset on Register File
The Reset Function (details the effect of the Reset input on each of the registers of the Serial Port.
SMSC LPC47M182
87
Revision 1.8 SMSC/Non-SMSC Register Sets (02-24-05)
DATASHEET
SMSC [ SMSC CORPORATION ]
