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M16C/64A Group
20. Real-Time Clock
20.1
Introduction
The real-time clock generates a 1-second signal from a count source and counts seconds, minutes,
hours, a.m./p.m., a day, and a week. It also detects matches with specified seconds, minutes, and hours.
Table 20.1 lists Real-Time Clock Specifications, Figure 20.1 shows a Real-Time Clock Block Diagram,
and Table 20.2 lists the I/O Port.
Table 20.1
Real-Time Clock Specifications
Item
Count source
Count operation
Count start condition
Count stop condition
Interrupt request generation timing
RTCOUT pin function
Read from timer
Write to timer
Selectable functions
Note:
1.
In this manual, day refers to one day of the week. Refer to 20.2.4 "Real-Time Clock Day Data
Register (RTCWK)" for details.
R01UH0136EJ0210 Rev.2.10
Jul 31, 2012
f1, fC
•
Increment
•
Compare mode 1 or not using compare mode
The count value is continuously used, and the count continues.
•
Compare mode 2
When a compare match is detected, the count value is set to 0
and the count continues.
•
Compare mode 3
When a compare match is detected, the count value is set to 0
and the count stops.
1 (count started) is written to the TSTART bit in the RTCCR1
register.
0 (count stopped) is written to the TSTART bit in the RTCCR1
register.
Select one of the following:
•
Update second data
•
Update minute data
•
Update hour data
•
Update day data
•
When day data is set to 000b
•
When time data and compare data match
Programmable I/O port or compare output
When the RTCSEC, RTCMIN, RTCHR, or RTCWK register is read,
the count value can be read. The values read from registers
RTCSEC, RTCMIN, and RTCHR are represented by the BCD code.
When bits TSTART and TCSTF in the RTCCR1 register are 0 (count
stopped), the RTCSEC, RTCMIN, RTCHR, and RTCWK registers
are write enabled. Values written to registers RTCSEC, RTCMIN,
and RTCHR are represented by the BCD code.
•
12-/24-hour mode switch function
•
Compare output
20. Real-Time Clock
Specification
Page 366 of 800
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