Endian Control Function; Figure 4-3: Big Endian Addresses Within Word; Figure 4-4: Little Endian Addresses Within Word - NEC V850E/CA1 ATOMIC Preliminary User's Manual

4.5.3 Endian control function

The endian control function can be used to set processing of word data in memory either by the Big
Endian method or the Little Endian method for each CS area selected with the chip select signal (CS0
to CS7). Switching of the endian method is specified with the endian configuration register (BEC).
(1) Endian configuration register (BEC)
This register can be read/written in 16-bit units.
15 14 13 12
BEC 0 BE70 0 BE60
CS7 CS6
Bit Position Bit Name
14, 12, 10, 8, BEn0
6, 4, 2, 0 (n = 0 to 7)
Cautions: 1. Bits 15, 13, 11, 9, 7, 5, 3, and 1 of the BEC register must be cleared (0). If these bits
are set to 1, the operation is not guaranteed.
2. Set the CSn area specified as the programmable peripheral I/O area to Little Endian
format (n = 0 to 7).
3. In the following areas, the data processing method is fixed to Little Endian method.
Any setting of Big Endian method for these areas according to the BEC register is
invalid.
- On-chip peripheral I/O area
- Internal ROM area
- Internal RAM area
- Fetch area of external memory
31
31
000BH
Chapter 4 Bus Control Function
11 10 9 8
0 BE50 0 BE40
CS5 CS4
Big Endian
Specifies the endian method.
BEn0
0 Little Endian method
1 Big Endian method

Figure 4-3: Big Endian Addresses within Word

24 23
0008H 0009H
0004H 0005H
0000H 0001H

Figure 4-4: Little Endian Addresses within Word

24 23
000AH
0007H 0006H
0003H 0002H
Preliminary User's Manual U14913EE1V0UM00
7 6 5 4 3
0 BE30 0 BE20 0
CS3 CS2 CS1
Function
Endian Control
16 17
000AH
0006H
0002H
16 17
0009H
0005H
0001H
2 1 0 Address
BE10 0 BE00 FFFFF068H
CS0
8 7 0
000BH
0007H
0003H
8 7 0
0008H
0004H
0000H
Initial
value
0000H
125