Datasheet

Section 2 CPU
Rev.4.00 Nov. 02, 2005 Page 33 of 304
REJ09B0143-0400
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 description on the data bus width and number of
accessing states of each register, refer to section 16.1, 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, access is completed in two cycles. 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
SUB
φ or φ
Figure 2.10 On-Chip Peripheral Module Access Cycle (3-State Access)