Datasheet

78K0/Kx2-L CHAPTER 10 REAL-TIME COUNTER
R01UH0028EJ0400 Rev.4.00 376
Sep 27, 2010
Figure 10-4. Format of Real-Time Counter Control Register 1 (RTCC1) (2/2)
RIFG Constant-period interrupt status flag
0 Constant-period interrupt is not generated.
1 Constant-period interrupt is generated.
This flag indicates the status of generation of the constant-period interrupt. When the constant-period interrupt is
generated, it is set to “1”.
This flag is cleared when “0” is written to it. Writing “1” to it is invalid.
RWST Wait status flag of real-time counter
0 Counter is operating.
1 Mode to read or write counter value
This status flag indicates whether the setting of RWAIT is valid.
Before reading or writing the counter value, confirm that the value of this flag is 1.
RWAIT Wait control of real-time counter
0 Sets counter operation.
1 Stops SEC to YEAR counters. Mode to read or write counter value
This bit controls the operation of the counter.
Be sure to write “1” to it to read or write the counter value.
Because RSUBC continues operation, complete reading or writing of it in 1 second, and clear this bit back to 0.
When RWAIT = 1, it takes up to 1 clock (32.768 kHz) until the counter value can be read or written.
If RSUBC overflows when RWAIT = 1, it counts up after RWAIT = 0. If the second count register is written,
however, it does not count up because RSUBC is cleared.
Caution If writing is performed to the RTCC1 register with a 1-bit manipulation instruction, the RIFG flag
and WAFG flag may be cleared. Therefore, to perform writing to the RTCC1 register, be sure to
use an 8-bit manipulation instruction. To prevent the RIFG flag and WAFG flag from being
cleared during writing, disable writing by setting 1 to the corresponding bit. If the RIFG flag and
WAFG flag are not used and the value may be changed, the RTCC1 register may be written by
using a 1-bit manipulation instruction.
Remark Fixed-cycle interrupts and alarm match interrupts use the same interrupt source (INTRTC). When using
these two types of interrupts at the same time, which interrupt occurred can be judged by checking the
fixed-cycle interrupt status flag (RIFG) and the alarm detection status flag (WAFG) upon INTRTC
occurrence.