CHAPTER 4 BUS CONTROL FUNCTION
User’s Manual U12688EJ4V0UM00
108
4.5.2 Bus sizing function
The V850E/MS1 is provided with a bus sizing function that is used to control the data bus width of each memory
block.
The data bus width is specified by using the bus size configuration register (BSC).
(1) Bus size configuration register (BSC)
This register can be read/written in 16-bit units.
15
BS71
BSC
Memory
block
Address
FFFFF066H
After reset
Note
14
BS70
13
BS61
12
BS60
11
BS51
10
BS50
9
BS41
8
BS40
7
BS31
6
BS30
5
BS21
4
BS20
3
BS11
2
BS10
1
BS01
0
BS00
7
6
5
4
3
2
1
0
Note When in single-chip modes 0, 1: 5555H
When in ROM-less mode 0:
5555H
When in ROM-less mode 1:
0000H
Bit Position
Bit Name
Function
Data Bus Width
Sets the data bus width of memory block n.
BSn1
BSn0
Data Bus Width of Memory Block n
0
0
8 bits
0
1
16 bits
1
Optional
RFU (Reserved)
15 to 0
BSn1,
BSn0
(n = 7 to 0)
Cautions 1. Write to the BSC register after reset, and then do not change the set value. Also, do not
access an external memory area other than the one for this initialization routine until the
initial setting of the BSC register is complete. However, it is possible to access an external
memory area whose initialization is complete.
2. The in-circuit emulator (IE-703102-MC) for the V850E/MS1 does not support 8-bit width
external ROM emulation.
3. When 8-bit data bus width is selected, only the write signal LWR becomes active, UWR
does not become active.
Summary of Contents for V850E/MS1 UPD703100
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