Rainbow Electronics W90N740 - Manual (Page 57)

W90N740
Publication Release Date: November 26, 2004
- 53 - Revision A4
External I/O Control Registers（EXT0CON – EXT3CON）
The W90N740 supports an external device control without glue logic. It is very cost effective because
address decoding and control signals timing logic are not needed. Using these control registers you can
configure special external I/O devices for providing the low cost external devices control solution.
Register Address R/W Description Reset Value
EXT0CON 0xFFF0.1018 R/W External I/O 0 control register 0x0000.0000
EXT1CON 0xFFF0.101C R/W External I/O 1 control register 0x0000.0000
EXT2CON 0xFFF0.1020 R/W External I/O 2 control register 0x0000.0000
EXT3CON 0xFFF0.1024 R/W External I/O 3 control register 0x0000.0000
31 30 29 28 27 26 25 24
BASADDR
23 22 21 20 19 18 17 16
BASADDR SIZE
15 14 13 12 11 10 9 8
ADRS tACC tCOH
7 6 5 4 3 2 1 0
tACS tCOS DBWD
BASADDR [31:19] ：Base address pointer of external I/O bank 0~3
The start address of each external I/O bank is calculated as “BASADDR” base pointer << 18.
Each external I/O bank base address pointer together with the “SIZE” bits constitutes the whole address
range of each external I/O bank.
SIZE [18:16] ：The size of the external I/O bank 0~3
SIZE [18:16] Byte
0 0 0 256K
0 0 1 512K
0 1 0 1M
0 1 1 2M
1 0 0 4M
1 0 1 8M
1 1 0 16M
1 1 1 32M