UPD78F0411GA-GAM-AX Datasheet, PDF (133/564 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

CHAPTER 5 CLOCK GENERATOR
(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, 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 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 the high-speed system clock or subsystem 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 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.
5.6.3 Example of controlling subsystem clock
The following two types of subsystem clocks are available.
• XT1 clock:
Crystal/ceramic resonator is connected across the XT1 and XT2 pins.
When the subsystem clock is not used, the XT1/P123 and XT2/P124 pins can be used as Input port pins.
Caution The XT1/P123 and XT2/P124 pins are in the Input port mode after a reset release.
The following describes examples of setting procedures for the following cases.
(1) When oscillating XT1 clock
(2) When using subsystem clock as CPU clock
(3) When stopping subsystem clock
User’s Manual U18698EJ1V0UD
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