HD6433044 Datasheet, PDF (442/867 Pages) Hitachi Semiconductor – Hitachi Single-Chip Microcomputer

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*
Note: * Lower 16 bits of the address.
H'5A
87
0
Write data
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.
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