Shifting To Stop Mode After Starting Operation - NEC 78K0R/KE3 User Manual

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 (f
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
RTCE = 1
Waiting at least for 2
f clocks
SUB
STOP mode
CHAPTER 7 REAL-TIME COUNTER
Sets to counter operation
start
Shifts to STOP mode
User's Manual U17854EJ9V0UD
μ
) (about 62 s) have elapsed after setting RTCE
SUB
Example 2
RTCE = 1
RWAIT = 1
RWST = 1 ?
No
Yes
RWAIT = 0
RWST = 0 ?
No
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
279