NEC V850E/CA1 ATOMIC, Preliminary User'S Manual

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Chapter 4 Bus Control Function
Preliminary User’s Manual U14913EE1V0UM00
4.5.4 Bus width
The V850E/CA1 / ATOMIC accesses peripheral I/O and external memory in 8-bit, 16-bit, or 32-bit units.
The following shows the operation for each type of access. Access all data in order starting from the
lower order side.
(1) Byte access (8 bits)
(a) When the data bus width is 16 bits (Little Endian)
<1> Access to even address (2n) <2> Access to odd address (2n + 1)
(b) When the data bus width is 8 bits (Little Endian)
<1> Access to even address (2n) <2> Access to odd address (2n + 1)
7
0
7
0
Byte data
15
8
External
data bus
2n
Address
7
0
7
0
Byte data
15
8
External
data bus
2n + 1
Address
7
0
7
0
Byte data External
data bus
2n
Address
7
0
7
0
Byte data External
data bus
2n + 1
Address