Datasheet

Product data sheet Rev. 1 — 19 February 2014 43 of 99

NXP Semiconductors

LPC15xx

32-bit ARM Cortex-M3 microcontroller

8.31 Repetitive Interrupt (RI) timer

The repetitive interrupt timer provides a free-running 48-bit counter which is compared to

a selectable value, generating an interrupt when a match occurs. Any bits of the

timer/compare can be masked such that they do not contribute to the match detection.

The repetitive interrupt timer can be used to create an interrupt that repeats at

predetermined intervals.

8.31.1 Features

• 48-bit counter running from the main clock. Counter can be free-running or can be

reset when an RIT interrupt is generated.

• 48-bit compare value.

• 48-bit compare mask. An interrupt is generated when the counter value equals the

compare value, after masking. This allows for combinations not possible with a simple

compare.

8.32 System tick timer

The ARM Cortex-M3 includes a system tick timer (SYSTICK) that is intended to generate

a dedicated SYSTICK exception at a fixed time interval (typically 10 ms).

8.33 Real-Time Clock (RTC)

The RTC resides in a separate, always-on voltage domain with battery back-up. The RTC

uses an independent 32 kHz oscillator, also located in the always-on voltage domain.

8.33.1 Features

• 32-bit, 1 Hz RTC counter and associated match register for alarm generation.

• Separate 16-bit high-resolution/wake-up timer clocked at 1 kHz for 1 ms resolution

with a more that one minute maximum time-out period.

• RTC alarm and high-resolution/wake-up timer time-out each generate independent

interrupt requests. Either time-out can wake up the part from any of the low power

modes, including Deep power-down.