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Philips Semiconductors
Preliminary User Manual
LPC2119/2129/2292/2294
ARM-based Microcontroller
11. UART1
FEATURES
• UART1 is identical to UART0, with the addition of a modem interface.
• 16 byte Receive and Transmit FIFOs.
• Register locations conform to ‘550 industry standard.
• Receiver FIFO trigger points at 1, 4, 8, and 14 bytes.
• Built-in baud rate generator.
• Standard modem interface signals included.
PIN DESCRIPTION
Table 86: UART1 Pin Description
Pin Name
Type
Description
RxD1
Input
Serial Input
. Serial receive data.
TxD1
Output
Serial Output
. Serial transmit data.
CTS1
Input
Clear To Send
. Active low signal indicates if the external modem is ready to accept transmitted
data via TxD1 from the UART1. In normal operation of the modem interface (U1MCR4=0), the
complement value of this signal is stored in U1MSR4. State change information is stored in
U1MSR0 and is a source for a priority level 4 interrupt, if enabled (U1IER3=1).
DCD1
Input
Data Carrier Detect
. Active low signal indicates if the external modem has established a
communication link with the UART1 and data may be exchanged. In normal operation of the
modem interface (U1MCR4=0), the complement value of this signal is stored in U1MSR7. State
change information is stored in U1MSR3 and is a source for a priority level 4 interrupt, if
enabled (U1IER3=1).
DSR1
Input
Data Set Ready
. Active low signal indicates if the external modem is ready to establish a
communications link with the UART1. In normal operation of the modem interface
(U1MCR4=0), the complement value of this signal is stored in U1MSR5. State change
information is stored in U1MSR1 and is a source for a priority level 4 interrupt, if enabled
(U1IER3=1).
DTR1
Output
Data Terminal Ready
. Active low signal indicates that the UART1 is ready to establish
connection with external modem. The complement value of this signal is stored in U1MCR0.
RI1
Input
Ring Indicator
. Active low signal indicates that a telephone ringing signal has been detected
by the modem. In normal operation of the modem interface (U1MCR4=0), the complement
value of this signal is stored in U1MSR6. State change information is stored in U1MSR2 and is
a source for a priority level 4 interrupt, if enabled (U1IER3=1).
RTS1
Output
Request To Send
. Active low signal indicates that the UART1 would like to transmit data to the
external modem. The complement value of this signal is stored in U1MCR1.