UM10237_2 © NXP B.V. 2008. All rights reserved.
User manual Rev. 02 — 19 December 2008 422 o f 792
1. Basic configuration
The UART0/2/3 peripherals are configured using the following registers:
1. Power: In the PCONP register (Tab le 4– 63), set bits PCUART0/2/3.
Remark: On reset, UART0 is enabled (PCUART0 = 1), and UART2/3 are disabled
(PCUART2/3 = 0).
2. Peripheral clock: In the PCLK_SEL0 register (Table4–56), select PCLK_UART0; in
the PCLK_SEL1 register (Table4–57), select PCLK_UART2/3.
3. Baud rate: In register U0/2/3LCR (Table 16–386), set bit DLAB =1. This enables
access to registers DLL (Table16–380) and DLM (Table 16–381) for setting the baud
rate. Also, if needed, set the fractional baud rate in the fractional divider register
(Table16–392).
4. UART FIFO: Use bit FIFO enable (bit 0) in register U0/2/3FCR (Table16–385) to
enable FIFO.
5. Pins: Select UART pins and pin modes in registers PINSELn and PINMODEn (see
Section 9–5).
Remark: UART receive pins should not have pull-down resistors enabled.
6. Interrupts: To enable UART interrupts set bit DLAB =0 in register U0/2/3LCR
(Table16–386). This enables access to U0/2/3IER (Table 16–382). Interrupts are
enabled in the VIC using the VICIntEnable register (Table7–106).
2. Features
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.
Fractional divider for baud rate control, autobaud capabilities and mechanism that
enables software flow control implementation.
In addition, UART3 includes an IrDA mode to support infrared communication.
3. Pin description
UM10237
Chapter 16: LPC24XX Universal Asynchronous Receiver/Transmitter (UART) 0/2/3
Rev. 02 — 19 December 2008 User manual
Table 376: UART0 Pin description
Pin Type Description
RXD0, RXD2, RXD3 Input Serial Input. Serial receive data.
TXD0, TXD2, TXD3 Output Serial Output. Serial transmit data.