Datasheet

78K0/Kx2-L CHAPTER 5 CLOCK GENERATOR
R01UH0028EJ0400 Rev.4.00 225
Sep 27, 2010
(3) Example of setting procedure when stopping the internal high-speed oscillation clock
The internal high-speed oscillation clock can be stopped in the following two ways.
• Executing the STOP instruction to set the STOP mode
• Setting RSTOP to 1 and stopping the internal high-speed oscillation clock
(a) To execute a STOP instruction
<1> Setting of peripheral hardware
Stop peripheral hardware that cannot be used in the STOP mode (for peripheral hardware that cannot be
used in STOP mode, refer to CHAPTER 19 STANDBY FUNCTION).
<2> Setting the X1 clock oscillation stabilization time after standby release
When the CPU is operating on the X1 clock, set the value of the OSTS register before the STOP
instruction is executed. To operate the CPU immediately after the STOP mode has been released, set
MCM0 to 0, switch the CPU clock to the internal high-speed oscillation clock, and check that RSTS is 1.
<3> Executing the STOP instruction
When the STOP instruction is executed, the system is placed in the STOP mode and internal high-speed
oscillation clock is stopped.
(b) To stop internal high-speed oscillation clock by setting RSTOP to 1
<1> Confirming the CPU clock status (PCC and MCM registers)
Confirm with CLS and MCS that the CPU is operating on a clock other than the internal high-speed
oscillation clock.
When CLS = 0 and MCS = 0, the internal high-speed oscillation clock is supplied to the CPU, so change
the CPU clock to a clock other than the internal high-speed oscillation clock.
• 78K0/KY2-L, 78K0/KA2-L, and 78K0/KB2-L
MCS CPU Clock Status
0 Internal high-speed oscillation clock
1 High-speed system clock
• 78K0/KC2-L
CLS MCS CPU Clock Status
0 0 Internal high-speed oscillation clock
0 1 High-speed system clock
1 × Subsystem clock
<2> Stopping the internal high-speed oscillation clock (RCM register)
When RSTOP is set to 1, internal high-speed oscillation clock is stopped.
Caution Be sure to confirm that MCS = 1 or CLS = 1 when setting RSTOP to 1. In addition, stop peripheral
hardware that is operating on the internal high-speed oscillation clock.