UPD78F1502AGK-GAK-AX Datasheet, PDF (379/1031 Pages) Renesas Technology Corp – 16-Bit Single-Chip Microcontrollers

78K0R/Lx3
CHAPTER 7 REAL-TIME COUNTER
7.4.2 Shifting to STOP mode after starting operation
Perform one of the following processing when shifting to STOP mode immediately after setting RTCE to 1.
However, after setting RTCE to 1, this processing is not required when shifting to STOP mode after the first INTRTC
interrupt has occurred.
• Shifting to STOP mode when at least two subsystem clocks (fSUB) (about 62 μ s) have elapsed after setting RTCE to 1
(see Figure 7-20, Example 1).
• Checking by polling RWST to become 1, after setting RTCE to 1 and then setting RWAIT to 1. Afterward, setting
RWAIT to 0 and shifting to STOP mode after checking again by polling that RWST has become 0 (see Figure 7-20,
Example 2).
Figure 7-20. Procedure for Shifting to STOP Mode After Setting RTCE to 1
Example 1
Example 2
RTCE = 1
Waiting at least for 2
fSUB clocks
STOP mode
Sets to counter operation
start
Shifts to STOP mode
No
RTCE = 1
RWAIT = 1
RWST = 1 ?
Yes
RWAIT = 0
No
RWST = 0 ?
Yes
STOP mode
Sets to counter operation
start
Sets to stop the SEC to YEAR
counters, reads the counter
value, write mode
Checks the counter wait status
Sets the counter operation
Shifts to STOP mode
R01UH0004EJ0501 Rev.5.01
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Jun 20, 2011