upd70f3402 Renesas Electronics Corporation., upd70f3402 Datasheet - Page 212

• Manufacturer Part Number: upd70f3402
• Description: 32-/16-bit Single-chip Microcontroller With Can Interface
• Manufacturer: Renesas Electronics Corporation.

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)
Caution:
Caution:
212
Symbol
BSC
R/W
CSn
Bus size configuration register (BSC)
This register can be read or written in 16-bit units.
signal
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.
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.
15
0
7
0
BSn0
0
1
Figure 5-2: Bus Size Configuration Register (BSC) Format
14
1
6
1
8 bits
16 bits
13
0
5
0
Chapter 5 Bus Control Function
User’s Manual U16702EE3V2UD00
Data bus width of CSn space (n = 0 to 1)
12
1
4
1
11
0
3
0
BS10
CS1
I__I
10
1
2
9
0
1
0
BS00
CS0
I__I
8
1
0
FFFFF066H
Address
After reset
5555H