Hardware manual

Microcomputer Technical Q&A
59
Q&A No.: QAH8S-050
Category: Power-Down State
Subject: Module Stop Mode
Question
When a write is performed on an 8-bit timer register, the value is not written. Why is this?
Answer
Immediately after a reset, an H8S Series chip enters module stop mode to hold down current
dissipation, and the internal I/O registers of the relevant modules cannot be read or written to.
Module stop mode should be cleared in advance for on-chip supporting modules that are to be
used.
Applicable Products
Applicability Series Applicability Series Applicability Series
Yes Entire H8S Series H8S/2655 H8S/2350
H8S/2355 H8S/2357 H8S/2345
H8S/2245 H8S/2148 H8S/2144
H8S/2138 H8S/2134 H8S/2128
H8S/2124 — — — —