EP7211 Datasheet, PDF (75/166 Pages) Cirrus Logic – HIGH-PERFORMANCE ULTRA-LOW-POWER SYSTEM-ON-CHIP WITH LCD CONTROLLER

EP7211
High-Performance Ultra-Low-Power System-on-Chip with LCD Controller
specification defines the behavior of the internal EP7211 registers in the Big Endian mode in more
detail.
The NCAS[3:0] lines for DRAM should always be connected with the same byte lane irrespective
of the Endianness, such that NCAS[0] will be connected with D[7:0], and NCAS[3] with D[31:24].
Thus, in a Little Endian system, NCAS[0] will be asserted for a read/write to byte 0 of DRAM and
in a big Endian system NCAS[3] will be asserted to access byte 0 of DRAM.
Table 3-16. Effect of Endianness on Read Operations
Address
(W/B)
Word + 0 (W)
Word + 1 (W)
Word + 2 (W)
Word + 3 (W)
Word + 0 (B)
Word + 1 (B)
Word + 2 (B)
Word + 3 (B)
Data in
Memory
11223344
11223344
11223344
11223344
11223344
11223344
11223344
11223344
Byte Lanes to Memory/Ports/Registers
Big Endian Memory
Little Endian Memory
7:0
15:8
23:1
6
31:2
4
7:0 15:8
23:1
6
31:2
4
44 33
22
11 44 33
22
11
44 33
22
11 44 33
22
11
44 33
22
11 44 33
22
11
44 33
22
11 44 33
22
11
dc dc
dc
11 44 dc
dc
dc
dc dc
22
dc dc 33
dc
dc
dc 33
dc
dc dc dc
22
dc
44 dc
dc
dc dc dc
dc
11
R0 Contents
Big
Endian
11223344
44112233
33441122
22334411
00000011
00000022
00000033
00000044
Little
Endian
11223344
44112233
33441122
22334411
00000044
00000033
00000022
00000011
NOTE: dc = don’t care
Table 3-17. Effect of Endianness on Write Operations
Address
(W/B)
Word + 0 (W)
Word + 1 (W)
Word + 2 (W)
Word + 3 (W)
Word + 0 (B)
Word + 1 (B)
Word + 2 (B)
Word + 3 (B)
Register
Contents
11223344
11223344
11223344
11223344
11223344
11223344
11223344
11223344
Byte Lanes to Memory/Ports/Registers
Big Endian Memory
Little Endian Memory
7:0 15:8 23:16 31:24 7:0 15:8 23:16 31:24
44
33
22
11
44
33
22
11
44
33
22
11
44
33
22
11
44
33
22
11
44
33
22
11
44
33
22
11
44
33
22
11
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
DS352PP3
JUL 2001
75
Functional Description