Endian Control Function - NEC V850E/MA1 User Manual

4.5.3 Endian control function

The endian control function can be used to set processing of word data in memory using either the big endian
method or the little endian method for each CS space selected with the chip select signals (CS0 to CS7). Switching of
the endian method is specified using the endian configuration register (BEC).
Caution In the following areas, the data processing method is fixed to little endian, so the setting of the
BEC register is invalid.
• • • • On-chip peripheral I/O area
• • • • Internal ROM area
• • • • Internal RAM area
• • • • Fetch area for external memory
(1) Endian configuration register (BEC)
This register can be read/written in 16-bit units.
Be sure to set bits 15, 13, 11, 9, 7, 5, 3, and 1 to 0. If they are set to 1, the operation is not guaranteed.
Caution Write to the BEC register after reset, and then do not change the set value.
15 14 13
BEC 0 BE70 0 BE60
CSn signal
CS7 CS6
Bit position Bit name
14, 12, 10, 8, BEn0
6, 4, 2, 0 (n = 0 to 7)
CHAPTER 4 BUS CONTROL FUNCTION
12 11 10 9 8 7
0 BE50 0 BE40 0
CS5 CS4
Big Endian
Specifies the endian method.
BEn0
0
Little endian method
1
Big endian method
User's Manual U14359EJ4V0UM
6 5 4 3 2 1
BE30 0 BE20 0 BE10 0
CS3 CS2 CS1
Function
Endian control
0
Address After reset
BE00
FFFFF068H
CS0
0000H
105