HD6413008VF25 Datasheet, PDF (362/688 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

11. Watchdog Timer
Writing to RSTCSR: RSTCSR must be written by a word transfer instruction. It cannot be
written by byte transfer instructions. Figure 11.3 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
15
87
0
Address H'FFF8E*
H'A5
H'00
Writing to RSTOE bit
15
Address H'FFF8E*
H'5A
87
0
Write data
Note: * Lower 20 bits of the address in advanced mode.
Figure 11.3 Format of Data Written to RSTCSR
Reading TCNT, TCSR, and RSTCSR: For reads of TCNT, TCSR, and RSTCSR, address
H'FFF8C is assigned to TCSR, address H'FFF8D to TCNT, and address H'FFF8F to RSTCSR.
These registers are therefore read like other registers. Byte transfer instructions can be used for
reading. Table 11.3 lists the read addresses of TCNT, TCSR, and RSTCSR.
Table 11.3 Read Addresses of TCNT, TCSR, and RSTCSR
Address*
Register
H'FFF8C
TCSR
H'FFF8D
TCNT
H'FFF8F
RSTCSR
Note: * Lower 20 bits of the address in advanced mode.
Rev.4.00 Aug. 20, 2007 Page 316 of 638
REJ09B0395-0400