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LPC2917_19_1
© NXP B.V. 2007. All rights reserved.
Preliminary data sheet
Rev. 1.01 — 15 November 2007
26 of 68
NXP Semiconductors
LPC2917/19
ARM9 microcontroller with CAN and LIN
8.4.3.4
Timer clock description
The timer modules are clocked by two different clocks; CLK_SYS_PESS and CLK_TMRx
(x = 0-3), see
Section 7.2.2
. Note that each timer has its own CLK_TMRx branch clock for
power management. The frequency of all these clocks is identical as they are derived
from the same base clock BASE_CLK_TMR. The register interface towards the system
bus is clocked by CLK_SYS_PESS. The timer and prescale counters are clocked by
CLK_TMRx.
8.4.4 UARTs
8.4.4.1
Overview
The LPC2917/19 contains two identical UARTs located at different peripheral base
addresses. The key features are:
•
16-byte receive and transmit FIFOs
•
Registers conform to industry standard 550
•
Receiver FIFO trigger points at 1 byte, 4 bytes, 8 bytes and 14 bytes
•
Built-in baud-rate generator
8.4.4.2
Description
The UART is commonly used to implement a serial interface such as RS232. The
LPC2917/19 contains two industry-standard 550 UARTs with 16-byte transmit and receive
FIFOs, but they can also be put into 450 mode without FIFOs.
8.4.4.3
UART pin description
The two UARTs in the LPC2917/19 have the following pins. The UART pins are combined
with other functions on the port pins of the LPC2917/19.
Table 15
shows the UART pins (x
runs from 0 to 1).
Table 14.
Timer pins
Symbol
Direction
Description
TIMERx CAP[0]
IN
TIMER x capture input 0
TIMERx CAP[1]
IN
TIMER x capture input 1
TIMERx CAP[2]
IN
TIMER x capture input 2
TIMERx CAP[3]
IN
TIMER x capture input 3
TIMERx MAT[0]
OUT
TIMER x match output 0
TIMERx MAT[1]
OUT
TIMER x match output 1
TIMERx MAT[2]
OUT
TIMER x match output 2
TIMERx MAT[3]
OUT
TIMER x match output 3
Table 15.
UART pins
Symbol
Direction
Description
UARTx TXD
out
UART channel x transmit data output
UARTx RXD
in
UART channel x receive data input