UPD78F0411GA-GAM-AX Datasheet, PDF (131/564 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

CHAPTER 5 CLOCK GENERATOR
(4) Example of setting procedure when stopping the high-speed system clock
The high-speed system clock can be stopped in the following two ways.
• Executing the STOP instruction to set the STOP mode
• Setting MSTOP to 1 and stopping the X1 oscillation (disabling clock input if the external clock is used)
(a) To execute a STOP instruction
<1> Setting to stop peripheral hardware
Stop peripheral hardware that cannot be used in the STOP mode (for peripheral hardware that
cannot be used in STOP mode, see 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.
<3> Executing the STOP instruction
When the STOP instruction is executed, the system is placed in the STOP mode and X1 oscillation
is stopped (the input of the external clock is disabled).
(b) To stop X1 oscillation (disabling external clock input) by setting MSTOP 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 high-speed system
clock.
When CLS = 0 and MCS = 1, the high-speed system clock is supplied to the CPU, so change the
CPU clock to the subsystem clock or internal high-speed oscillation clock.
CLS
MCS
CPU Clock Status
0
0
Internal high-speed oscillation clock
0
1
High-speed system clock
1
×
Subsystem clock
<2> Stopping the high-speed system clock (MOC register)
When MSTOP is set to 1, X1 oscillation is stopped (the input of the external clock is disabled).
Caution Be sure to confirm that MCS = 0 or CLS = 1 when setting MSTOP to 1. In addition, stop
peripheral hardware that is operating on the high-speed system clock.
5.6.2 Example of controlling internal high-speed oscillation clock
The following describes examples of clock setting procedures for the following cases.
(1) When restarting oscillation of the internal high-speed oscillation clock
(2) When using internal high-speed oscillation clock as CPU clock, and internal high-speed oscillation clock or
high-speed system clock as peripheral hardware clock
(3) When stopping the internal high-speed oscillation clock
User’s Manual U18698EJ1V0UD
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