SH7729R Datasheet, PDF (312/855 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer Super RISC engine Family/SH7700 Series

1. Clear the WT/IT bit in the WTCSR register to 0, set the type of count clock in the CKS2–
CKS0 bits, and set the initial value of the counter in the WTCNT counter.
2. Set the TME bit in WTCSR to 1 to start the count in interval timer mode.
3. When the counter overflows, the WDT sets the IOVF flag in WTCSR to 1 and an interval
timer interrupt request is sent to the INTC. The counter then resumes counting.
10.9 Notes on Board Design
When Using an External Crystal Resonator: Place the crystal resonator, capacitors CL1 and
CL2, and damping resistor R close to the EXTAL and XTAL pins. To prevent induction from
interfering with correct oscillation, use a common grounding point for the capacitors connected to
the resonator, and do not locate a wiring pattern near these components.
Avoid crossing
signal lines
CL1
CL2
EXTAL
R
XTAL
SH7729R
Note: The values for CL1, CL2, and the damping resistance should be determined after
consultation with the crystal manufacturer.
Figure 10.4 Points for Attention when Using Crystal Resonator
Decoupling Capacitors: Insert a laminated ceramic capacitor of 0.01 to 0.1 µF as a passive
capacitor for each V_SS/V_CC pair. Mount the passive capacitors close to the SH7729R power supply
pins, and use components with a frequency characteristic suitable for the chip’s operating
frequency, as well as a suitable capacitance value.
Digital system V_SS/V_CC pairs: 19-21, 27-29, 33-35, 45-47, 57-59, 69-71, 79-81, 83-85, 95-97, 109-
111, 132-134, 153-154, 161-163, 173-175, 181-183, 205-208
On-chip oscillator V_SS/V_CC pairs: 3-6, 145-147, 148-150
When Using a PLL Oscillator Circuit: Keep the wiring from the PLL V_CC and V_SS connection
pattern to the power supply pins short, and make the pattern width large, to minimize the
Rev. 5.0, 09/03, page 266 of 806