r5f21368sdfp Renesas Electronics Corporation., r5f21368sdfp Datasheet - Page 130

• Manufacturer Part Number: r5f21368sdfp
• Description: Renesas Mcu R8c Family / R8c/3xt-a Series
• Manufacturer: Renesas Electronics Corporation.

Under development
R8C/36T-A Group
R01UH0240EJ0001 Rev.0.01
Apr 28, 2011
9.7
Table 9.6
9.7.1
Clock frequency range for oscillation
stop detection
Condition for enabling the oscillation
stop detection function
Operation at oscillation stop detection
The oscillation stop detection function is used to detect whether the XIN clock oscillation is stopped.
The oscillation stop detection function can be enabled or disabled with the OCD0 bit in the OCD register.
Table 9.6 lists the Oscillation Stop Detection Function Specifications.
When the XIN clock is the CPU clock source and bits OCD1 and OCD0 are 11b, if the XIN clock is stopped, the
states will change as follows:
• Bits CM42 to CM40 in CM4 register = 001b (fLOCO)
• CM14 bit in CM1 register = 0 (low-speed on-chip oscillator on).
• An oscillation stop detection interrupt is generated
• The oscillation stop detection interrupt shares a vector with the watchdog timer, voltage monitor 1, and
• When the XIN clock reoscillates after oscillation is stopped, switch the XIN clock to the clock source for the
• When entering wait mode while using the oscillation stop detection function, set the CM02 bit in the CM0
• Since the oscillation stop detection function is a function for cases where the XIN clock is stopped by an
• This function cannot be used when the XIN clock frequency is below 2 MHz. In this case, set bits OCD1 and
• To use the low-speed on-chip oscillator clock for the clock source for the CPU clock and the peripheral
voltage monitor 2 interrupts. To use both the oscillation stop detection and watchdog timer interrupts, the
interrupt source needs to be determined.
Table 9.7 shows How to Determine Interrupt Source for Oscillation Stop Detection Interrupt, Watchdog Timer
Interrupt, Voltage Monitor 1 Interrupt, or Voltage Monitor Interrupt. Figure 9.6 shows an Example of How to
Determine Interrupt Sources for Oscillation Stop Detection Interrupt, Watchdog Timer Interrupt, Voltage
Monitor 1 Interrupt, or Voltage Monitor 2 Interrupt.
CPU clock and the peripheral functions by a program.
Figure 9.5 shows the Procedure for Switching from Low-Speed On-Chip Oscillator to XIN Clock.
register to 0 (function clock does not stop in wait mode).
external cause, set bits OCD1 and OCD0 to 00b to stop or oscillate the XIN clock by a program (to select stop
mode or change the CM05 bit in the CM05 register).
OCD0 to 00b.
functions after oscillation stop is detected, set the OCD6 bit in the OCD register 0 (low-speed on-chip
oscillator selected) before setting bits OCD1 and OCD0 to 11b.
To use the high-speed on-chip oscillator clock is used for the clock source for the CPU clock and the
peripheral functions after oscillation stop is detected, set the FRA00 bit in the FRA0 register to 1 (high-speed
on-chip oscillator on) and the OCD6 bit to 1 (high-speed on-chip oscillator selected) before setting bits OCD1
and OCD0 to 11b.
Oscillation Stop Detection Function
How to Use Oscillation Stop Detection Function
Preliminary document
Specifications in this document are tentative and subject to change.
Oscillation Stop Detection Function Specifications
Item
f(XIN)
Set bits OCD1 and OCD0 in the OCD register to 11b.
An oscillation stop detection interrupt is generated.

2 MHz
Specification
9. Clock Generation Circuit
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