h8s-2646 Renesas Electronics Corporation., h8s-2646 Datasheet - Page 455

• Manufacturer Part Number: h8s-2646
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2600 Series
• Manufacturer: Renesas Electronics Corporation.

12.2.4
The watchdog timer’s TCNT, TCSR, and RSTCSR registers differ from other registers in being
more difficult to write to. The procedures for writing to and reading these registers are given
below.
Writing to TCNT and TCSR: These registers must be written to by a word transfer instruction.
They cannot be written to with byte instructions.
Figure 12.2 shows the format of data written to TCNT and TCSR. TCNT and TCSR both have the
same write address. For a write to TCNT, the upper byte of the written word must contain H'5A
and the lower byte must contain the write data. For a write to TCSR, the upper byte of the written
word must contain H'A5 and the lower byte must contain the write data. This transfers the write
data from the lower byte to TCNT or TCSR.
TCNT write
TCSR write
Notes on Register Access
Address: H'FF74
Address: H'FF74
Figure 12.2 Format of Data Written to TCNT and TCSR (WDT0)
15
15
H'5A
H'A5
Rev. 5.00 Sep 22, 2005 page 429 of 1136
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Section 12 Watchdog Timer
Write data
Write data
REJ09B0257-0500
0
0