UART1 152 May 03, 2004
Philips Semiconductors Preliminary User Manual
LPC2119/2129/2194/2292/2294ARM-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.
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