HD6417618 RENESAS [Renesas Technology Corp], HD6417618 Datasheet - Page 245

• Manufacturer Part Number: HD6417618
• Description: 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7618 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

9.3.2
To change the multiplication ratio of PLL circuit 1, use the WDT. When changing the frequency
only by switching the divider, do not use the WDT.
1. Before changing the frequency, always clear the TME bit in WTCSR to 0. When the TME bit
2. Set the type of count clock used in the CKS2 to CKS0 bits in WTCSR and the initial values for
3. When bits STC2 to STC0 in the frequency control register (FRQCR) is written, the processor
4. When the WDT count overflows, the CPG resumes supplying the clock and the processor
5. WTCNT stops at the value of H'00.
6. Before changing WTCNT after the execution of the frequency change instruction, always
9.3.3
1. Set the WT/IT bit in WTCSR to 1, set the type of count clock in bits CKS2 to CKS0, and set
2. Set the TME bit in WTCSR to 1 to start the count in watchdog timer mode.
3. While operating in watchdog timer mode, rewrite the counter periodically to H'00 to prevent
4. When the counter overflows, the WDT sets the WOVF flag in WTCSR to 1 and generates a
is 1, an erroneous reset or interval timer interrupt may be generated when the count overflows.
the counter in WTCNT. These values should ensure that the time till count overflow is longer
than the clock oscillation settling time.
stops temporarily. The WDT starts counting.
resumes operation. The WOVF flag in WTCSR is not set when this happens.
confirm that the value of WTCNT is H'00 by reading WTCNT.
the initial value of the counter in WTCNT.
the counter from overflowing.
power-on reset. WTCNT then resumes counting.
Changing Frequency
Using Watchdog Timer Mode
Rev. 6.00 Jun. 12, 2007 Page 213 of 610
Section 9 Watchdog Timer (WDT)
REJ09B0131-0600