W90N740CD WINBOND [Winbond], W90N740CD Datasheet - Page 43

• Manufacturer Part Number: W90N740CD
• Description: 32-Bit ARM7TDMI-Based Micro-Controller
• Manufacturer: WINBOND [Winbond]

6.3.3
The W90N740 can receive and acknowledge bus request signals that are generated by an external
bus master. When the CPU asserts an external bus acknowledge signal, mastership is granted to the
external bus master, assuming the external bus request is still active.
When the external bus acknowledge signal is active, the W90N740’s memory interface signals go to
high impedance state so that the external bus master can drive the required external memory
interface signals.
The W90N740 does not perform SDRAM refreshes when it is not the bus master. When an external
bus master is in control of the external bus, and if it retains control for a long period of time, it must
assume the responsibility of performing the necessary SDRAM refresh operations.
6.3.4
EBI Control Register (EBICON)
REGISTER
EBICON
REGISTER
SDCONF0
SDCONF1
EXT0CON
EXT1CON
EXT2CON
EXT3CON
ROMCON
SDTIME0
SDTIME1
CKSKEW
EBICON
31
23
15
7
External Bus Mastership
EBI Control Registers Map
0xFFF0.1000
0xFFF0.100C
0xFFF0.101C
0xFFF0.1000
0xFFF0.1004
0xFFF0.1008
0xFFF0.1010
0xFFF0.1014
0xFFF0.1018
0xFFF0.1020
0xFFF0.1024
0xFFF0.1F00
ADDRESS
ADDRESS
30
22
14
6
RESERVED
REFRAT
29
21
13
5
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
ROM/FLASH control register
SDRAM bank 0 configuration register
SDRAM bank 1 configuration register
External I/O 0 control register
External I/O 1 control register
External I/O 2 control register
External I/O 3 control register
EBI control register
SDRAM bank 0 timing control register
SDRAM bank 1 timing control register
Clock skew control register
28
20
12
EBI control register
4
RESERVED
REFRAT
- 40 -
W90N740CD/W90N740CDG
DESCRIPTION
DESCRIPTION
27
19
11
3
REFEN
26
18
10
2
WAITVT
REFMOD
25
17
9
1
RESET VALUE
RESET VALUE
0xXXXX.0038
0x0000.0XFC
0x0001.0000
0x0000.0800
0x0000.0800
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0001.0000
CLKEN
LITTLE
24
16
8
0