R01UH0823EJ0100 Rev.1.00
Page 179 of 1823
Jul 31, 2019
RX23W Group
9. Clock Generation Circuit
9.2.7
Main Clock Oscillator Control Register (MOSCCR)
Note:
Set the PRCR.PRC0 bit to 1 (write enabled) before rewriting this register.
Set this register after setting up the main clock oscillator wait control register.
MOSTP Bit (Main Clock Oscillator Stop)
This bit runs or stops the main clock oscillator.
After setting the MOSTP bit to 0 (main clock oscillator is operating), read the OSCOVFSR.MOOVF bit to confirm that
is has become 1, and then use the main clock.
For the main clock oscillator, a fixed time is required for oscillation to become stable after the settings for operation have
been made. Furthermore, a fixed time is required for oscillation to actually stop after the settings to stop oscillation have
been made. Accordingly, take note of the following limitations when starting and stopping operation.
After stopping the main clock oscillator, confirm that the OSCOVFSR.MOOVF bit is 0 before restarting the main
clock oscillator.
Confirm that the main clock oscillator is operating and that the OSCOVFSR.MOOVF bit is 1 before stopping the
main clock oscillator.
Regardless of whether or not it is selected as the system clock, confirm that the OSCOVFSR.MOOVF bit is 1 and
execute a WAIT instruction in order to operate the main clock oscillator and place the MCU in software standby
mode.
After stopping the main clock oscillator, confirm that the OSCOVFSR.MOOVF bit is 0 and execute a WAIT
instruction before entering software standby mode.
Do not set the MOSTP bit to 1 when one of the following condition is met.
When the main clock is selected as the clock source for the system clock (SCKCR3.CKSEL[2:0] = 010b)
When the PLL clock is selected as the clock source for the system clock (SCKCR3.CKSEL[2:0] = 100b)
When the PLL is operating (PLLCR2.PLLEN = 0)
When the USB-dedicated PLL is operating (UPLLCR2.PLLEN = 0)
Do not set the MOSTP bit to 0 when the following condition is met.
When low-speed operating mode is selected by the SOPCCR.SOPCM bit
Address(es): 0008 0032h
b7
b6
b5
b4
b3
b2
b1
b0
—
—
—
—
—
—
—
MOSTP
Value after reset:
0
0
0
0
0
0
0
1
Bit
Symbol
Bit Name
Description
R/W
b0
Main Clock Oscillator Stop
0: Main clock oscillator is operating.
1: Main clock oscillator is stopped.
R/W
b7 to b1
—
Reserved
These bits are read as 0. The write value should be 0.
R/W