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Chapter 31 External Bus
4.Endian and Bus Access
● 8-bit bus width
Figure 4-12 External Bus Access for 8-Bit Bus Width
■ Example of Connection with External Devices
Figure 4-13 "Example of Connecting the MB91460 Series to External Devices" shows an example of connection
the MB91460 series to external devices.
11
10
01
00
11
10
01
00
11
10
01
00
11
10
01
00
(a) PA1/PA0="00"
(1) Output
A1/A0="00"
(b) PA1/PA0="01"
(1) Output
A1/A0="00"
(c) PA1/PA0="10"
(1) Output
A1/A0="10"
(d) PA1/PA0="11"
(1) Output
A1/A0="10"
(1)
(1)
(1)
(1)
LSBMSB
11
10
01
(1)
(2)
(3)
(4)
(1)
(2)
(3)
(4)
(1)
(2)
(3)
(4)
(1)
(2)
(3)
(4)
8bit
00
11
10
01
00
11
10
01
00
11
10
01
00
(a) PA1/PA0="00"
(1) Output
A1/A0="00"
(2) Output
A1/A0="01"
(3) Output
1/A0="10"
(4) Output
1/A0="11"
(b) PA1/PA0="01"
(1) Output
A1/A0="00"
(2) Output
A1/A0="01"
(3) Output
1/A0="10"
(4) Output
1/A0="11"
(c) PA1/PA0="10"
(1) Output
A1/A0="00"
(2) Output
A1/A0="01"
(3) Output
1/A0="10"
(4) Output
1/A0="11"
(d) PA1/PA0="11"
(1) Output
A1/A0="00"
(2) Output
A1/A0="01"
(3) Output
1/A0="10"
(4) Output
1/A0="11"
(A) Word access
(B) Halfword access
(C) Byte access
11
10
01
00
11
10
01
00
11
10
01
00
11
10
01
00
(a) PA1/PA0="00"
(1) Output
A1/A0="00"
(2) Output
A1/A0="01"
(b) PA1/PA0="01"
(1) Output
A1/A0="00"
(2) Output
A1/A0="01"
(c) PA1/PA0="10"
(1) Output
A1/A0="10"
(2) Output
A1/A0="11"
(d) PA1/PA0="11"
(1) Output
A1/A0="10"
(2) Output
A1/A0="11"
(1)
(2)
(1)
(2)
(1)
(2)
(1)
(2)