r5f21346mnfp Renesas Electronics Corporation., r5f21346mnfp Datasheet - Page 170

• Manufacturer Part Number: r5f21346mnfp
• Description: Single-chip Mcus Incorporates The R8c Cpu Core
• Manufacturer: Renesas Electronics Corporation.

R8C/34M Group
R01UH0131EJ0100 Rev.1.00
Jun 21, 2011
9.8.1
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The oscillation stop detection interrupt shares a vector with the voltage monitor 1 interrupt, the voltage
monitor 2 interrupt, and the watchdog timer interrupt. To use the oscillation stop detection interrupt and
watchdog timer interrupt, the interrupt source needs to be determined.
Table 9.7 lists the Determination of Interrupt Sources for Oscillation Stop Detection, Watchdog Timer,
Voltage Monitor 1, or Voltage Monitor 2 Interrupt. Figure 9.10 shows an Example of Determining Interrupt
Sources for Oscillation Stop Detection, Watchdog Timer, Voltage Monitor 1, or Voltage Monitor 2 Interrupt.
When the XIN clock restarts after oscillation stop, switch the XIN clock to the clock source for the CPU clock
and the peripheral functions by a program.
Figure 9.9 shows the Procedure for Switching to XIN Clock when XIN Clock Re-Oscillates after Oscillation
Stop is Detected.
To enter wait mode while the oscillation stop detection function is used, set the CM02 bit to 0 (peripheral
function clock does not stop in wait mode).
Since the oscillation stop detection function is a function for cases where the XIN clock is stopped by an
external cause, set bits OCD1 to OCD0 to 00b to stop or start the XIN clock by a program (select stop mode or
change the CM05 bit).
This function cannot be used when the XIN clock frequency is below 2 MHz. In this case, set bits OCD1 to
OCD0 to 00b.
To use the low-speed on-chip oscillator clock as the clock source for the CPU clock and the peripheral
functions after detecting the oscillation stop, set the FRA01 bit in the FRA0 register to 0 (low-speed on-chip
oscillator selected) and bits OCD1 to OCD0 to 11b.
To use the high-speed on-chip oscillator clock as the clock source for the CPU clock and the peripheral
functions after detecting the oscillation stop, first set the FRA00 bit to 1 (high-speed on-chip oscillator
oscillates) and the FRA01 bit to 1 (high-speed on-chip oscillator selected). Then set bits OCD1 to OCD0 to
11b.
How to Use Oscillation Stop Detection Function
9. Clock Generation Circuit
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