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Chapter 11
RTC Time Base Timer (RTC-TBT)
11.1 Overview
RTC time base timer (RTC-TBT) generates 1 Hz clock with SCLK of 32.768 kHz for Real Time Clock (RTC).
11.1.1
Functions
Table:11.1.1 shows the function of RTC-TBT.
Clock source
Interrupt
Adjustment for the 1 Hz clock period When selecting 32.768 kHz clock,
XI - 2
Overview
Table:11.1.1 RTC-TBT Function
Function
SOSCCLK
SRCCLK
TBTCNT0.TBTCLKSEL
Figure:11.1.1 RTC-TBT Block Diagram
SCLK (SOSCCLK or SRCCLK is selected.)
Frequency of RTC-TBT interrupt
1 Hz, 2 Hz, 4 Hz, 8 Hz, 16 Hz, 32 Hz, 64 Hz, 128 Hz
(In the case of SCLK of 32.768 kHz)
Range:
Period of 128 sec:
- 488 ppm to
Period of 32 sec: - 1954 ppm to + 1952 ppm
Period of
8 sec: - 7813 ppm to + 7805 ppm
Period of
2 sec: - 31250 ppm to + 31220 ppm
Accuracy:
Period of 128 sec: 0.48 ppm
Period of 32 sec: 1.92 ppm
Period of
8 sec: 7.63 ppm
Period of
2 sec: 30.52 ppm
7 bit counter
8 bit counter
Description
+ 488 ppm
T128HZ
T64HZ
T32HZ
8
T16HZ
T8HZ
T4HZ
T2HZ
T1HZ
Frequency
Adjustment
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