Freescale Semiconductor MPC5604B - Overview

MPC5604B/C Microcontroller Reference Manual, Rev. 8
Freescale Semiconductor 243
Chapter 13
Real Time Clock / Autonomous Periodic Interrupt (RTC/API)
13.1 Overview
The RTC/API is a free running counter used for time keeping applications. The RTC may be configured
to generate an interrupt at a predefined interval independent of the mode of operation (run mode or low
power mode). If in a low power mode when the RTC interval is reached, the RTC first generates a wakeup
and then assert the interrupt request. The RTC also supports an autonomous periodic interrupt (API)
function used to generate a periodic wakeup request to exit a low power mode or an interrupt request.
13.2 Features
Features of the RTC/API include:
• 3 selectable counter clock sources
— SIRC (128 kHz)
— SXOSC (32 KHz)
— FIRC (16 MHz)
• Optional 512 prescaler and optional 32 prescaler
• 32-bit counter
— Supports times up to 1.5 months with 1 ms resolution
— Runs in all modes of operation
— Reset when disabled by software and by POR
• 12-bit compare value to support interrupt intervals of 1 s up to greater than 1 hr with 1 s resolution
• RTC compare value changeable while counter is running
• RTC status and control register are reset only by POR
• Autonomous periodic interrupt (API)
— 10-bit compare value to support wakeup intervals of 1.0 ms to 1 s
— Compare value changeable while counter is running
• Configurable interrupt for RTC match, API match, and RTC rollover
• Configurable wakeup event for RTC match, API match, and RTC rollover