SERIAL PORT (UART)
The FDC37M60x incorporates two full function
UARTs. They are compatible with the
NS16450, the 16450 ACE registers and the
NS16550A. The UARTS perform serial-to-
parallel conversion on received characters and
parallel-to-serial conversion on transmit
by programming UT2 of that UART to a logic
"1". OUT2 being a logic "0" disables that
UART's interrupt. The second UART also
supports IrDA, HP-SIR, and ASK-IR infrared
modes of operation.
characters. The data rates are independently
programmable from 460.8K baud down to 50
baud. The character options are programmable
for 1 start; 1, 1.5 or 2 stop bits; even, odd, sticky
or no parity; and prioritized interrupts. The
UARTs each contain a programmable baud rate
generator that is capable of dividing the input
clock or crystal by a number from 1 to 65535.
The UARTs are also capable of supporting the
MIDI data rate. Refer to the Configuration
Registers for information on disabling, power
down and changing the base address of the
UARTs. The interrupt from a UART is enabled
Note: The UARTs may be configured to share
an interrupt. Refer to the Configuration section
for more information.
REGISTER DESCRIPTION
Addressing of the accessible registers of the
Serial Port is shown below.
The base
addresses of the serial ports are defined by the
configuration registers (see Configuration
section). The Serial Port registers are located at
sequentially increasing addresses above these
base addresses. The FDC37M60x contains two
serial ports, each of which contain a register set
as described below.
Table 31 - Addressing the Serial Port
DLAB*
A2
0
0
0
0
0
0
1
1
1
1
0
0
A1
0
0
0
1
1
1
0
0
1
1
0
0
A0
0
0
1
0
0
1
0
1
0
1
0
1
REGISTER NAME
Receive Buffer (Read)
0
0
Transmit Buffer (Write)
0
Interrupt Enable (Read/Write)
Interrupt Identification (Read)
FIFO Control (Write)
X
X
X
X
X
X
X
1
Line Control (Read/Write)
Modem Control (Read/Write)
Line Status (Read/Write)
Modem Status (Read/Write)
Scratchpad (Read/Write)
Divisor LSB (Read/Write)
Divisor MSB (Read/Write)
1
*Note: DLAB is Bit 7 of the Line Control Register
66
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