Table of Contents
Advertisement
5.1
Overview
The H8/3937 Series and H8/3937R Series have nine modes of operation after a reset. These
include eight power-down modes, in which power dissipation is significantly reduced. Table 5-1
gives a summary of the eight operating modes.
Table 5-1
Operating Modes
Operating Mode
Active (high-speed) mode
Active (medium-speed) mode
Subactive mode
Sleep (high-speed) mode
Sleep (medium-speed) mode
Subsleep mode
Watch mode
Standby mode
Module standby mode
Of these nine operating modes, all but the active (high-speed) mode are power-down modes. In
this section the two active modes (high-speed and medium speed) will be referred to collectively
as active mode.
Figure 5-1 shows the transitions among these operation modes. Table 5-2 indicates the internal
states in each mode.
Section 5 Power-Down Modes
Description
The CPU and all on-chip peripheral functions are operable on the
system clock in high-speed operation. The FLEX™ decoder is
independently operable on the subclock.
The CPU and all on-chip peripheral functions are operable on the
system clock in low-speed operation. The FLEX™ decoder is
independently operable on the subclock.
The CPU is operable on the subclock in low-speed operation. The
FLEX™ decoder is independently operable on the subclock.
The CPU halts. On-chip peripheral functions are operable on the
system clock. The FLEX™ decoder is independently operable on
the subclock.
The CPU halts. On-chip peripheral functions operate at a
frequency of 1/64, 1/32, 1/16, or 1/8 of the system clock frequency.
The FLEX™ decoder is independently operable on the subclock.
The CPU halts. Timer A, timer C, timer G, timer F, the WDT, SCI1,
SCI31, SCI32, and the FLEX™ decoder are operable on the
subclock.
The timer A time-base function, timer F, timer G, and the FLEX™
decoder are operable on the subclock.
The CPU and all on-chip peripheral functions halt. The FLEX™
decoder is independently operable on the subclock.
Individual on-chip peripheral functions specified by software enter
standby mode and halt.
95
Advertisement
Table of Contents
