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5.4.2 Bus size setting function
The bus size of each external memory area selected by CSn can be set (to 8 bits or 16 bits) by using
the BSC register.
The external memory area of the V850E/RS1 (0000000H to 03FFFFFH) is selected by CS0 and CS1.
(1)
Bus size configuration register (BSC)
This register can be read or written in 16-bit units.
Caution:
Symbol
BSC
R/W
CSn
Caution:
212
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Chapter 5 Bus Control Function
Write to the BSC register after reset, and then do not change the set values. Also, do
not access an external memory area other than the one for this initialization routine
until the initial settings of the BSC register are complete. However, external memory
areas whose initial settings are complete may be accessed.
Figure 5-2: Bus Size Configuration Register (BSC) Format
15
14
13
0
1
0
7
6
5
0
1
0
signal
BSn0
0
8 bits
1
16 bits
Be sure to set bits 14, 12, 10, 8, 6, 4 to 1, and clear bits 15, 13, 11, 9, 7, 5, 3, 1 to 0.
User's Manual U16702EE3V2UD00
12
11
10
9
1
0
1
0
4
3
2
1
1
0
BS10
0
I__I
CS1
Data bus width of CSn space (n = 0 to 1)
8
Address
After reset
1
FFFFF066H
5555H
0
BS00
I__I
CS0
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