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.
