Technical information

7-36
AIC-6915 Ethernet LAN Controller Programmer’s Manual
GPIO Register
Type: R/W
Internal Registers Subgroup: Ethernet Functional Registers
Byte Address: 8C - 8Fh
The
GPIO
register provides for host software control of the
GPIO[3:0]
pins.
Table 7-45. GPIO Register
Bit(s) rw
Reset
Value Description/Function
31:28 r 0
Reserved:
Always written as ‘0’.
27:24 r/w 1111
GPIOCtrl[3:0]:
If any of these bits are set, the corresponding
GPIO
bit is configured as an input. Otherwise it is an output.
23:20 r 0
Reserved:
Always written as ‘0’.
19:16 r/w 0
GPIOOutMode[3:0]:
Active only when the corresponding
GPIO
pin is configured as an output. Bit 0 controls
GPIO[0]
, bit 1
controls
GPIO[1]
, etc.
‘
0
’ - Regular output.
‘
1
’ - Open Drain output.
15:8 r/w 0
GPIOInpMode[7:0]:
Active only when the corresponding
GPIO
pin is configured as an input. Bits [1:0] control
GPIO[0]
, Bits[3:2]
control
GPIO[1]
etc.
‘
00
’ - Regular input.
‘
01
’ - Corresponding interrupt status bit is set when the
GPIO
input is high.
‘
10
’ - Corresponding interrupt status bit is set when the
GPIO
input is low.
‘
11
’ - Corresponding interrupt status bit is set when the
GPIO
input is changing.
7:4 r 0 Reserved: Always reads 0.
3:0 r/w depends
on input
value
GPIOData[3:0]:
Reading the port gives the value on the
GPIO[3:0]
pins. Writing the port is effective only for those GPIO
pins configured as outputs. In this case the written value is driven
to the output.