AMD Geode LX [email protected] User Manual
Page 39
AMD Geode™ LX Processors Data Book
39
33234H
DEVSEL#
AK25
I/O
33-66 Mb/s
3.3
Device Select. DEVSEL# indicates that the driv-
ing device has decoded its address as the target
of the current access. As an input, DEVSEL#
indicates whether any device on the bus has
been selected. DEVSEL# is also driven by any
agent that has the ability to accept cycles on a
subtractive decode basis. As a master, if no
DEVSEL# is detected within and up to the sub-
tractive decode clock, a master abort cycle
results, except for special cycles that do not
expect a DEVSEL# returned.
REQ[2:0]#
AB28,
AB31,
AA29
I
33-66 Mb/s
3.3
Request Lines. REQ# indicates to the arbiter
that an agent desires use of the bus. Each mas-
ter has its own REQ# line. REQ# priorities are
based on the arbitration scheme chosen.
REQ2# is reserved for the interface with the
AMD Geode CS5536 companion device.
GNT[2:0]#
AC30,
AB30,
AA28
(Strap)
I/O
33-66 Mb/s
3.3
Grant Lines. GNT# indicates to the requesting
master that it has been granted access to the
bus. Each master has its own GNT# line. GNT#
can be pulled away any time a higher REQ# is
received or if the master does not begin a cycle
within a set period of time.
GNT# is an output during normal operation. It is
an input at reset and functions as a boot strap for
frequency selection on a board. It must be pulled
high or low to invoke the strap.
GNT2# is reserved for the interface with the
AMD Geode CS5536 companion device.
3.4.5
PCI Interface Signals (Continued)
Signal Name
Ball No.
Type
f
V
Description