Renesas R5S72621 User Manual
Section 13 Watchdog Timer
Page 668 of 2108
R01UH0134EJ0400 Rev. 4.00
Sep
24,
2014
SH7262 Group, SH7264 Group
13.3.4
Notes on Register Access
The watchdog timer counter (WTCNT), watchdog timer control/status register (WTCSR), and
watchdog reset control/status register (WRCSR) are more difficult to write to than other registers.
The procedures for reading or writing to these registers are given below.
watchdog reset control/status register (WRCSR) are more difficult to write to than other registers.
The procedures for reading or writing to these registers are given below.
(1) 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.
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 13.2. 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.
as shown in figure 13.2. 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.
H'5A
15
8
7
0
H'A5
15
8
7
0
Write data
Address: H'FFFE0002
WTCNT write
Write data
Address: H'FFFE0000
WTCSR write
Figure 13.2 Writing to WTCNT and WTCSR