Renesas F-ZTAT H8 Series, Hardware Manual

Page: 81 / 562

2. CPU
Rev.3.00 Jul. 19, 2007 page 55 of 532
REJ09B0397-0300
Legend:
op:
Operation field
15 0 8 7
op
op
Figure 2.10 Block Data Transfer Instruction Code
2.6 Basic Operational Timing
CPU operation is synchronized by a system clock (
φ
) or a subclock (
φ
SUB
). For details on these
clock signals see section 4, Clock Pulse Generators. The period from a rising edge of
φ
or
φ
SUB
to
the next rising edge is called one state. A bus cycle consists of two states or three states. The cycle
differs depending on whether access is to on-chip memory or to on-chip peripheral modules.
2.6.1 Access to On-Chip Memory (RAM, ROM)
Access to on-chip memory takes place in two states. The data bus width is 16 bits, allowing access
in byte or word size. Figure 2.11 shows the on-chip memory access cycle.
T
1
state
Bus cycle
T
2
state
Internal address bus
Internal read signal
Internal data bus
(read access)
Internal write signal
Read data
Address
Write data
Internal data bus
(write access)
SUB
φ
or
φ
Figure 2.11 On-Chip Memory Access Cycle