112
Philips Semiconductors
Preliminary User Manual
LPC2119/2129/2292/2294
ARM-based Microcontroller
UART0 Transmitter Holding Register (U0THR - 0xE000C000 when DLAB = 0, Write Only)
The U0THR is the top byte of the UART0 Tx FIFO. The top byte is the newest character in the Tx FIFO and can be written via
the bus interface. The LSB represents the first bit to transmit.
The Divisor Latch Access Bit (DLAB) in U0LCR must be zero in order to access the U0THR. The U0THR is always Write Only.
UART0 Divisor Latch LSB Register (U0DLL - 0xE000C000 when DLAB = 1)
UART0 Divisor Latch MSB Register (U0DLM - 0xE000C004 when DLAB = 1)
The UART0 Divisor Latch is part of the UART0 Baud Rate Generator and holds the value used to divide the VPB clock (pclk) in
order to produce the baud rate clock, which must be 16x the desired baud rate. The U0DLL and U0DLM registers together form
a 16 bit divisor where U0DLL contains the lower 8 bits of the divisor and U0DLM contains the higher 8 bits of the divisor. A ‘h0000
value is treated like a ‘h0001 value as division by zero is not allowed.The Divisor Latch Access Bit (DLAB) in U0LCR must be
one in order to access the UART0 Divisor Latches.
Table 75: UART0 Receiver Buffer Register (U0RBR - 0xE000C000 when DLAB = 0, Read Only)
U0RBR
Function
Description
Reset
Value
7:0
Receiver Buffer
Register
The UART0 Receiver Buffer Register contains the oldest received byte in the UART0 Rx
FIFO.
un-
defined
Table 76: UART0 Transmit Holding Register (U0THR - 0xE000C000 when DLAB = 0, Write Only)
U0THR
Function
Description
Reset
Value
7:0
Transmit
Holding Register
Writing to the UART0 Transmit Holding Register causes the data to be stored in the
UART0 transmit FIFO. The byte will be sent when it reaches the bottom of the FIFO and
the transmitter is available.
N/A
Table 77: UART0 Divisor Latch LSB Register (U0DLL - 0xE000C000 when DLAB = 1)
U0DLL
Function
Description
Reset
Value
7:0
Divisor Latch
LSB Register
The UART0 Divisor Latch LSB Register, along with the U0DLM register, determines the
baud rate of the UART0.
0x01
Table 78: UART0 Divisor Latch MSB Register (U0DLM - 0xE000C004 when DLAB = 1)
U0DLM
Function
Description
Reset
Value
7:0
Divisor Latch
MSB Register
The UART0 Divisor Latch MSB Register, along with the U0DLL register, determines the
baud rate of the UART0.
0