Renesas H8/3067 Series User Manual page 494

Section 12 Watchdog Timer
Writing to RSTCSR: RSTCSR must be written by a word transfer instruction. It cannot be
written by byte transfer instructions. Figure 12.3 shows the format of data written to RSTCSR. To
write 0 in the WRST bit, the write data must have H'A5 in the upper byte and H'00 in the lower
byte. The data (H'00) in the lower byte is written to RSTCSR, clearing the WRST bit to 0. To
write to the RSTOE bit, the upper byte must contain H'5A and the lower byte must contain the
write data. Writing this word transfers a write data value into the RSTOE bit.
Writing 0 in WRST bit
Address
Writing to RSTOE bit
Address
Note: Lower 20 bits of the address in advanced mode.
*
Reading TCNT, TCSR, and RSTCSR: These registers are read like other registers. Reading
TCNT, TCSR, and RSTCSR: These registers are read like other registers. Byte transfer
instructions can be used. The read addresses are H'FFF8C for TCSR, H'FFF8D for TCNT, and
H'FFF8F for RSTCSR, as listed in table 12-3.
Table 12.3 Read Addresses of TCNT, TCSR, and RSTCSR
Address*
H'FFF8C
H'FFF8D
H'FFF8F
Note: * Lower 20 bits of the address in advanced mode.
Rev. 4.00 Jan 26, 2006 page 470 of 938
REJ09B0276-0400
15
H'FFF8E*
15
H'FFF8E*
Figure 12.3 Format of Data Written to RSTCSR
Register
TCSR
TCNT
RSTCSR
8 7
H'A5
8 7
H'5A
0
H'00
0
Write data