Power-Down State; Basic Operational Timing; Overview; On-Chip Memory Access Timing - Hitachi H8/3062 Hardware Manual

2.8.7

Power-Down State

In the power-down state the CPU stops operating to conserve power. There are three modes: sleep
mode, software standby mode, and hardware standby mode.
Sleep Mode: A transition to sleep mode is made if the SLEEP instruction is executed while the
SSBY bit is cleared to 0 in the system control register (SYSCR). CPU operations stop
immediately after execution of the SLEEP instruction, but the contents of CPU registers are
retained.
Software Standby Mode: A transition to software standby mode is made if the SLEEP
instruction is executed while the SSBY bit is set to 1 in SYSCR. The CPU and clock halt and all
on-chip supporting modules stop operating. The on-chip supporting modules are reset, but as long
as a specified voltage is supplied the contents of CPU registers and on-chip RAM are retained.
The I/O ports also remain in their existing states.
Hardware Standby Mode: A transition to hardware standby mode is made when the STBY input
goes low. As in software standby mode, the CPU and all clocks halt and the on-chip supporting
modules are reset, but as long as a specified voltage is supplied, on-chip RAM contents are
retained.
For further information see section 21, Power-Down State.
2.9

Basic Operational Timing

2.9.1

Overview

The H8/300H CPU operates according to the system clock (ø). The interval from one rise of the
system clock to the next rise is referred to as a "state." A memory cycle or bus cycle consists of
two or three states. The CPU uses different methods to access on-chip memory, the on-chip
supporting modules, and the external address space. Access to the external address space can be
controlled by the bus controller.
2.9.2

On-Chip Memory Access Timing

On-chip memory is accessed in two states. The data bus is 16 bits wide, permitting both byte and
word access. Figure 2.15 shows the on-chip memory access cycle. Figure 2.16 indicates the pin
states. All H8/3062 Series models except the H8/3062F-ZTAT have a function for changing the
method of outputting addresses from the address pins. For details see section 6.3.5, Address
Output Method.
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