h8s-2172 Renesas Electronics Corporation., h8s-2172 Datasheet - Page 321

• Manufacturer Part Number: h8s-2172
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family H8s-2100 Series
• Manufacturer: Renesas Electronics Corporation.

10.5
10.5.1
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:
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 10.6 to write to TCNT or TCSR. To write to TCNT, the higher 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 higher bytes must contain the value H'A5 and the
lower bytes must contain the write data.
Reading from TCNT and TCSR:
These registers are read in the same way as other registers. The read address is H'FE70 for TCSR
and H'FE71 for TCNT.
<TCNT write>
<TCSR write>
Usage Notes
Notes on Register Access
Address :
Address :
H'FE70
H'FE70
Figure 10.6 Writing to TCNT and TCSR
0
0
15
15
H'5A
H'A5
8 7
8 7
Rev. 2.00, 03/04, page 289 of 534
Write data
Write data
0
0