Interface To Bus Master; 16-Bit Registers; Figure 12.2 16-Bit Register Access Operation [Bus Master ↔ Tcnt (16 Bits)] - Renesas H8S Series Hardware Manual

12.4

Interface to Bus Master

12.4.1

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 from 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 12.2.
Internal data bus
H
Bus
L
master
Figure 12.2 16-Bit Register Access Operation [Bus Master ↔ TCNT (16 Bits)]
12.4.2 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 12.3, 12.4, and 12.5.
Bus interface
Section 12 16-Bit Timer Pulse Unit (TPU)
TCNTH TCNTL
Rev. 3.00 Jul. 14, 2005 Page 333 of 986
Module
data bus
REJ09B0098-0300