NXP Semiconductors MC9S08LG16, Reference Manual

Page: 297 / 373

MC9S08LG32 MCU Series, Rev. 5
Freescale Semiconductor 297
Chapter 15
Real-Time Counter (S08RTCV1)
15.1 Introduction
The Real-Time Counter (RTC) module consists of one 8-bit counter, one 8-bit comparator, several
binary-based and decimal-based prescaler dividers, three clock sources, and one programmable periodic
interrupt. This module can be used for time-of-day, calendar, or any task scheduling functions. It can also
serve as a cyclic wake up from low-power modes without the need of external components.
NOTE
For details on low-power mode operation, refer to Table 3-2 in Chapter 3,
“Modes of Operation .”
15.1.1 RTC Clock Gating
The bus clock to the RTC can be gated on and off using the RTC bit in SCGC1. This bit is cleared after
any reset, which disables the bus clock to this module. To conserve power, this bit can be cleared to disable
the clock to this module when not in use. For more details, see
Section 5.7, “Peripheral Clock Gating .”