HD6417615 Hitachi Semiconductor, HD6417615 Datasheet - Page 680

• Manufacturer Part Number: HD6417615
• Description: Hardware Manual
• Manufacturer: Hitachi Semiconductor

16.3
16.3.1
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 16.2.
16.3.2
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 16.3, 16.4, and 16.5.
668
Bus
master
Bus
master
Figure 16.3 8-Bit Register Access Operation [Bus Master
Figure 16.2 16-Bit Register Access Operation [Bus Master
Interface to Bus Master
16-Bit Registers
8-Bit Registers
Internal data bus
H
Internal data bus
L
H
L
Bus interface
Bus interface
TCNTH
TCR
TCR (Upper 8 Bits)]
TCNTL
TCNT (16 Bits)]
Module
data bus
Module
data bus