DM9000A
APPLICATION NOTES
Preliminary 8
Version: DM9000A-AN-V121
November 27, 2007
2.1.1 Pin Function Table
Note: The pins of processor parallel interface all have a pulled down resistor about 60K Ohm
internally.
Processor
Bus Signal
DM9000A
Signal
Pin No. I/O Description
nRD
IOR#
35
I
Processor READ Command
This pin is low active at default; its polarity can be modified by the
EEPROM setting.
nWR
IOW#
36
I
Processor WRITE Command
This pin is low active at default; its polarity can be changed by the
EEPROM setting.
nCS /
nAEN
CS# 37 I
Chip
Select
A low active signal is used to select the DM9000A. Its polarity can be
changed by the EEPROM setting.
SD0 ~ 7
SD0 ~ 7
18,17,16
14,13,12
,11,10
I/O DATA Bus 0 ~ 7
SD8 ~ 15
SD8 ~ 15 31,29,28
27,26,25
,24,22
I/O DATA Bus 8 ~ 15 (in 16-bit mode)
CMD CMD 32
I
Command
Type
When low, the access of this command cycle is INDEX port
When high, the access of this command cycle is DATA port
INT INT
34
O
Interrupt
Request
This pin is high active and open-collected at default; its polarity and its
output type can be modified by the EEPROM setting.
Table 2.1 Pin Function Table for Processor Interface
2.1.2 8/ 16-Bit Mode Setting
There are two operation modes of DATA bus width, 8-bit or 16-bit, when access to the internal
memory in the DM9000A. These two modes are selected by the strap pin 21 EECS shown the
following table:
EECS (pin 21)
DATA width
0
16-bit
1
8-bit
Where, "1" means pull-high with the 10K Ohm resistor, and "0" means floating (default).
The status of DATA width operation mode can be examined from Bit [7] of ISR REG. FEH,
ISR (REG. FEH) IOMODE (DATA width)
Bit
[7]
Operation
0
16-bit
mode
1
8-bit
mode