
Rev. 2.0, 09/02, page 148 of 732
9.10
Access to On-chip Peripheral I/O Registers
On-chip peripheral I/O registers are accessed from the bus state controller as shown in table 9.3.
Refer to section 25, List of Registers, for more details.
Table 9.3 Access to On-chip Peripheral I/O Registers
On-chip
peripheral
module
SCI
MTU,
POE
INTC
PFC,
PORT
CMT
A/D
UBC
WDT
DMAC
DTC
IIC
H-UDI
Connection
bus width
8
bits
16
bits
16
bits
16
bits
16
bits
8
bits
16
bits
16
bits
16
bits
16
bits
8
bits
16
bits
Number of
access
cycles
2
cyc
2
cyc
2
cyc
2
cyc
2
cyc
3
cyc
3
cyc
3
cyc
3
cyc
3
cyc
2
cyc
2
cyc
9.11
Cycles of No-Bus Mastership Release
The bus mastership is not released during one bus cycle. For example, when the longword read (or
write) access is performed to the 8-bit normal space, four memory accesses to the 8-bit normal
space are regarded as one bus cycle. In this bus cycle, the bus mastership is not released. In this
case, assuming that one memory access takes two states, the bus mastership is not released in eight
states.
8 bits
8 bits
8 bits
8 bits
Cycle in which the bus
mastership is not released
Figure 9.16 One Bus Cycle
9.12
CPU Operation When Program Is Located in External Memory
In this LSI, two words (two instructions) are fetched in one instruction fetch. This also applies to
the cases where program is located in external memory or the bus width of that external memory is
8 or 16 bits.
Also, if the program counter value is the odd word (2n+1) address or the program counter value
before branch is the even word (2n) address, 32 bits (two instructions) including each word
instruction are always fetched.