h8s-2161b Renesas Electronics Corporation., h8s-2161b Datasheet - Page 410

• Manufacturer Part Number: h8s-2161b
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2100 Series
• Manufacturer: Renesas Electronics Corporation.

Section 14 Watchdog Timer (WDT)
14.6
14.6.1
The watchdog timer’s registers, TCNT and TCSR differ from other registers in being more
difficult to write to. The procedures for writing to and reading from these registers are given
below.
Writing to TCNT and TCSR (Example of WDT_0): These registers must be written to by a
word transfer instruction. They cannot be written to by a byte transfer instruction.
TCNT and TCSR both have the same write address. Therefore, satisfy the relative condition
shown in figure 14.6 to write to TCNT or TCSR. To write to TCNT, the upper bytes must contain
the value H'5A and the lower bytes must contain the write data before the transfer instruction
execution. To write to TCSR, the upper bytes must contain the value H'A5 and the lower bytes
must contain the write data.
Reading from TCNT and TCSR (Example of WDT_0): These registers are read in the same
way as other registers. The read address is H'FFA8 for TCSR and H'FFA9 for TCNT.
Rev. 3.00 Mar 21, 2006 page 356 of 788
REJ09B0300-0300
<TCSR write>
<TCNT write>
Usage Notes
Notes on Register Access
Address : H'FFA8
Address : H'FFA8
Figure 14.6 Writing to TCNT and TCSR (WDT_0)
0
0
15
15
H'5A
H'A5
8 7
8 7
Write data
Write data
0
0