32.2.1 Features
The RTC module features include:
• 32-bit seconds counter with roll-over protection and 32-bit alarm
• 16-bit prescaler with compensation that can correct errors between 0.12 ppm and
3906 ppm
• Register write protection
• Lock register requires POR or software reset to enable write access
• 1 Hz square wave output with optional interrupt
32.2.2 Modes of operation
The RTC remains functional in all low power modes and can generate an interrupt to exit
any low power mode.
32.2.3 RTC signal descriptions
Table 32-1. RTC signal descriptions
Signal
Description
I/O
RTC_CLKOUT
1 Hz square-wave output or OSCERCLK
O
32.2.3.1 RTC clock output
The clock to the seconds counter is available on the RTC_CLKOUT signal. It is a 1 Hz
square wave output. See
32.3 Register definition
All registers must be accessed using 32-bit writes and all register accesses incur three
wait states.
Write accesses to any register by non-supervisor mode software, when the supervisor
access bit in the control register is clear, will terminate with a bus error.
Read accesses by non-supervisor mode software complete as normal.
Register definition
KL27 Sub-Family Reference Manual , Rev. 5, 01/2016
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Freescale Semiconductor, Inc.
