LPC2917 datasheet(25/68 Pages) PHILIPS

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LPC2917_19_1

Preliminary data sheet

Rev. 1.01 — 15 November 2007

25 of 68

NXP Semiconductors

LPC2917/19

ARM9 microcontroller with CAN and LIN

timer has four capture inputs and/or match outputs. Connection to device pins depends on

the configuration programmed into the port function-select registers. The two timers

located in the MSCSS have no external capture or match pins, but the memory map is

identical, see Section 8.7.7. One of these timers has an external input for a pause

function.

The key features are:

• 32-bit timer/counter with programmable 32-bit prescaler

• Up to four 32-bit capture channels per timer. These take a snapshot of the timer value

when an external signal connected to the TIMERx CAPn input changes state. A

capture event may also optionally generate an interrupt

• Four 32-bit match registers per timer that allow:

– Continuous operation with optional interrupt generation on match

– Stop timer on match with optional interrupt generation

– Reset timer on match with optional interrupt generation

• Up to four external outputs per timer corresponding to match registers, with the

following capabilities:

– Set LOW on match

– Set HIGH on match

– Toggle on match

– Do nothing on match

• Pause input pin (MSCSS timers only)

8.4.3.2

Description

The timers are designed to count cycles of the clock and optionally generate interrupts or

perform other actions at specified timer values, based on four match registers. They also

include capture inputs to trap the timer value when an input signal changes state,

optionally generating an interrupt. The core function of the timers consists of a 32 bit

‘prescale counter’ triggering the 32 bit ‘timer counter’. Both counters run on clock

CLK_TMRx (x runs from 0 to 3) and all time references are related to the period of this

clock. Note that each timer has its individual clock source within the Peripheral

SubSystem. In the Modulation and Sampling SubSystem each timer also has its own

individual clock source. See section Section 8.8.6 for information on generation of these

clocks.

8.4.3.3

Pin description

The four timers in the peripheral subsystem of the LPC2917/19 have the pins described

below. The two timers in the modulation and sampling subsystem have no external pins

except for the pause pin on MSCSS timer 1. See Section 8.7.7 for a description of these

timers and their associated pins. The timer pins are combined with other functions on the

port pins of the LPC2917/19, see Section 8.3.3. Table Table 14 shows the timer pins (x

runs from 0 to 3).

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