HD6432345 Datasheet, PDF (338/907 Pages) Hitachi Semiconductor – H8S/2345 F-ZTAT Hardware Manual

9.3 Interface to Bus Master
9.3.1 16-Bit Registers
TCNT and TGR are 16-bit registers. As the data bus to the bus master is 16 bits wide, these
registers can be read and written to in 16-bit units.
These registers cannot be read or written to in 8-bit units; 16-bit access must always be used.
An example of 16-bit register access operation is shown in figure 9.2.
Internal data bus
H
Bus
master ^L
Bus interface
Module
data bus
TCNTH
TCNTL
Figure 9.2 16-Bit Register Access Operation [Bus Master ↔ TCNT (16 Bits)]
9.3.2 8-Bit Registers
Registers other than TCNT and TGR are 8-bit. As the data bus to the CPU is 16 bits wide, these
registers can be read and written to in 16-bit units. They can also be read and written to in 8-bit
units.
Examples of 8-bit register access operation are shown in figures 9.3, 9.4, and 9.5.
Bus
master
Internal data bus
H
L
Bus interface
Module
data bus
TCR
Figure 9.3 8-Bit Register Access Operation [Bus Master ↔ TCR (Upper 8 Bits)]
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