H8S2245 datasheet(436/818 Pages) RENESAS

Part #	H8S2245

Description	Renesas 16-Bit Single-Chip Microcomputer H8S Family / H8S/2200 Series

PDF	818 Pages

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Manufacturer	RENESAS [Renesas Technology Corp]

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Section 11 Watchdog Timer

Rev.3.00 Mar. 26, 2007 Page 394 of 772

REJ09B0355-0300

11.2.4

Notes on Register Access

The watchdog timer's TCNT, TCSR, and RSTCSR registers differ from other registers in being

more difficult to write to. The procedures for writing to and reading these registers are given

below.

Writing to TCNT and TCSR

These registers must be written to by a word transfer instruction. They cannot be written to with

byte instructions.

Figure 11.2 shows the format of data written to TCNT and TCSR. TCNT and TCSR both have the

same write address. For a write to TCNT, the upper byte of the written word must contain H'5A

and the lower byte must contain the write data. For a write to TCSR, the upper byte of the written

word must contain H'A5 and the lower byte must contain the write data. This transfers the write

data from the lower byte to TCNT or TCSR (see figure 11.2).

TCNT write

TCSR write

Address: H'FFBC

H'5A

Write data

8 7

H'A5

Write data

8 7

Figure 11.2 Format of Data Written to TCNT and TCSR

H8S2245 Datasheet(PDF) 436 Page - Renesas Technology Corp