SH7615 Datasheet, PDF (724/925 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperH
RISC engine Family/SH7600 Series

16.3 Interface to Bus Master
16.3.1 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 16.2.
Internal data bus
H
Bus
master ^L
Bus interface
Module
data bus
TCNTH
TCNTL
Figure 16.2 16-Bit Register Access Operation [Bus Master ↔ TCNT (16 Bits)]
16.3.2 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 16.3, 16.4, and 16.5.
Bus
master
Internal data bus
H
L
Bus interface
Module
data bus
TCR
Figure 16.3 8-Bit Register Access Operation [Bus Master ↔ TCR (Upper 8 Bits)]
Rev. 2.00, 03/05, page 686 of 884