HD6417606 RENESAS [Renesas Technology Corp], HD6417606 Datasheet - Page 235

• Manufacturer Part Number: HD6417606
• Manufacturer: RENESAS [Renesas Technology Corp]

9.2.3
The watchdog timer counter (WTCNT) and watchdog timer control/status register (WTCSR) are
more difficult to write to than other registers. The procedure for writing to these registers is given
below.
Writing to WTCNT and WTCSR: These registers must be written by a word transfer
instruction. They cannot be written by a byte or longword transfer instruction. When writing to
WTCNT, set the upper byte to H'5A and transfer the lower byte as the write data, as shown in
figure 9.2. When writing to WTCSR, set the upper byte to H'A5 and transfer the lower byte as the
write data. This transfer procedure writes the lower byte data to WTCNT or WTCSR.
Bit
2
1
0
Notes on Register Access
Bit Name
CKS2
CKS1
CKS0
Initial
Value
0
0
0
R/W
R/W
R/W
R/W
Description
Clock Select 2 to 0
These bits select the clock to be used for the WTCNT
count from the eight types obtainable by dividing the
peripheral clock (Pφ). The overflow period that is
shown inside the parenthesis in the table is the value
when the peripheral clock (Pφ) is 25 MHz.
000: Pφ (10 µs)
001: Pφ /4 (41 µs)
010: Pφ /16 (164 µs)
011: Pφ /32 (328 µs)
100: Pφ /64 (655 µs)
101: Pφ /256 (2.62 ms)
110: Pφ /1024 (10.49 ms)
111: Pφ /4096 (41.94 ms)
Note: If bits CKS2 to CKS0 are modified when the
WDT is operating, the up-count may not be
performed correctly. Ensure that these bits are
modified only when the WDT is not operating.
Rev. 4.00 Sep. 13, 2007 Page 209 of 502
Section 9 Watchdog Timer (WDT)
REJ09B0239-0400