Endian Setting Function; Endian Configuration Register (Bec); Endian Configuration Register (Bec) - Renesas NU85E Preliminary User's Manual

4.6 Endian Setting Function

4.6.1 Endian configuration register (BEC)

The endian setting function uses the endian configuration register (BEC) to set the endian format of word data
within memory for each CSn area selected by the chip select signals (VDCSZn) (see Figures 4-3 and 4-4) (n = 7 to
0).
The BEC register can be read or written in 16-bit units.
Cautions 1. Set the CSn area specified as the programmable peripheral I/O area in the little endian format
(n = 7 to 0).
2. Each of the following areas is fixed at little endian format. Any setting of the big endian
format for these areas according to the BEC register is invalid.
• • • • Peripheral I/O area
• • • • ROM area
• • • • RAM area
• • • • The area that is the same as the RAM area and that is located at address 3FFEFFFH and
below (for 256 MB mode) (See Figure 3-8 Data Area (256 MB Mode))
• • • • External memory fetch area (when VMBSTR signal is active)
15 14 13
BE BE
BEC 0 0
70
Bit position Bit name
14, 12, 10, BEn0
8, 6, 4, 2, 0
Remark n = 7 to 0
Caution Always set bits 15, 13, 11, 9, 7, 5, 3, and 1 to 0. If they are set to 1, operation is not
guaranteed.
CHAPTER 4 BCU
Figure 4-8. Endian Configuration Register (BEC)
12 11 10 9 8 7
BE BE
0 0 0
60 50 40
Sets the endian format of word data in the CSn area.
BEn0
0 Little endian format (see Figure 4-9)
1 Big endian format (see Figure 4-10)
Preliminary User's Manual A14874EJ3V0UM
6 5 4 3 2
BE BE BE
0 0
30 20 10
Function
Endian format
1 0
BE Address After reset
0
00 FFFFF068H 0000H
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