Datasheet

Section 2 CPU
Rev. 2.00 Sep. 23, 2005 Page 35 of 444
REJ09B0068-0200
2.6.2 On-Chip Peripheral Modules
On-chip peripheral modules are accessed in two states or three states. The data bus width is 8 bits
or 16 bits depending on the register. For details on the data bus width and number of access states
of each register, refer to section 20.1, Register Addresses (Address Order). Registers with 16-bit
data bus width can be accessed by word size only. Registers with 8-bit data bus width can be
accessed by byte or word size. When a register with 8-bit data bus width is accessed by word size,
a bus cycle occurs twice. In two-state access, the operation timing is the same as that for on-chip
memory.
Figure 2.10 shows the operation timing in the case of three-state access to an on-chip peripheral
module.
T
1
state
Bus cycle
Internal
address bus
Internal
read signal
Internal
data bus
(read access)
Internal
write signal
Read data
Address
Internal
data bus
(write access)
T
2
state T
3
state
Write data
φ
Figure 2.10 On-Chip Peripheral Module Access Cycle (3-State Access)