Hardware manual

Microcomputer Technical Q&A
22
Q&A No.: QAH8S-019
Category: MCU Operating Modes
Subject: Mode Pins
Questions
1. Is it possible to change the MCU operating mode during normal operation?
2. Is there any way of fixing the MCU operating mode (preventing a change of MCU operating
mode due to noise, etc.)?
Answers
1. The MCU operating mode cannot be changed during normal operation, as this would cause
misoperation.
2. Read the memory control register (MDCR). When MDCR is read, the input levels of the mode
pins (MD2 to MD0)
*1
are latched in the corresponding bits. As these latches are cleared by a
power-on reset but not by a manual reset
*2
, a change of MCU operating mode during operation
can be prevented in this way.
Notes: 1. In the H8S/2100 Series, the mode pins are MD1 and MD0.
2. There is no manual reset in the H8S/2100 Series.
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 — — — —