Datasheet

Table Of Contents
Section 12 Watchdog Timer (WDT)
REJ09B0140-0900 Rev. 9.00 Page 377 of 846
Sep 16, 2010
H8S/2215 Group
Writing to RSTCSR: RSTCSR must be written to by a word transfer to address H'FF76. It cannot
be written to with byte instructions. Figure 12.7 shows the format of data written to RSTCSR. The
method of writing 0 to the WOVF bit differs from that for writing to the RSTE and RSTS bits.
To write 0 to the WOVF bit, the upper byte of the written word must contain H'A5 and the lower
byte must contain H'00. This clears the WOVF bit to 0, but has no effect on the RSTE and RSTS
bits. To write to the RSTE and RSTS bits, the upper byte must contain H'5A and the lower byte
must contain the write data. This writes the values in bits 6 and 5 of the lower byte into the RSTE
and RSTS bits, but has no effect on the WOVF bit.
Writing 0 to WOVF bit
Write to RSTE, RSTS bits
Address: H'FF76
Address: H'FF76
H'A5 H'00
15 8 7 0
H'5A Write data
15 8 7 0
Figure 12.7 Format of Data Written to RSTCSR (Example of WDT0)
Reading from TCNT, TCSR, and RSTCSR: TCNT, TCSR, and RSTCSR are read by using the
same method as for the general registers. TCSR, TCNT, and RSTCSR are allocated in addresses
H'FF74, H'FF75, and H'FF77 respectively.