HD64F3048F16 Datasheet, PDF (476/903 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

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 H'00 in the
lower byte clears the WRST bit in RSTCSR 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
15
87
0
Address H'FFAA^*
H'A5
H'00
Writing to RSTOE bit
15
Address H'FFAA^*
H'5A
87
0
Write data
Note: * Lower 16 bits of the address.
Figure 12.3 Format of Data Written to RSTCSR
Reading TCNT, TCSR, and RSTCSR
These registers are read like other registers. Byte access instructions can be used. The read
addresses are H'FFA8 for TCSR, H'FFA9 for TCNT, and H'FFAB for RSTCSR, as listed in table
12.3.
Table 12.3 Read Addresses of TCNT, TCSR, and RSTCSR
Address^*
Register
H'FFA8
TCSR
H'FFA9
TCNT
H'FFAB
RSTCSR
Note: * Lower 16 bits of the address.
Rev. 3.00 Sep 27, 2006 page 448 of 872
REJ09B0325-0300