PXD10RM Datasheet, PDF (1083/1332 Pages) Freescale Semiconductor, Inc – PXD10 Microcontroller

Chapter 31
Real-Time Clock (RTC/API)
31.1 Overview
The RTC 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 will first generate 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.
31.2 Features
Features of the RTC include:
• 4 selectable counter clock sources
— 4–16 MHz FXOSC
— 128 kHz SIRC
— 32 kHz SXOSC
— 16 MHz FIRC
• 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 1s up to greater than 1 hr with 1s 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
Freescale Semiconductor
PXD10 Microcontroller Reference Manual, Rev. 1
Preliminary—Subject to Change Without Notice
31-1