Kontron 886LCD-M/ATX User Manual page 31

KTD-00474-U Public
AGP/PCI Signals-Semantics
G_FRAME: Frame.
FRAME#
During PIPE# and SBA Operation: Not used by AGP SBA and PIPE# operations.
During Fast Write Operation: Used to frame transactions as an output during Fast
Writes.
During FRAME# Operation: G_FRAME# is an output when the GMCH acts as an initiator on
the AGP Interface. G_FRAME# is asserted by the GMCH to indicate the beginning and duration
of an access. G_FRAME# is an input when the GMCH acts
as a FRAME#-based AGP target. As a FRAME#-based AGP target, the GMCH latches the
C/BE[3:0]# and the AD[31:0] signals on the first clock edge on which GMCH samples FRAME#
active.
IRDY# G_IRDY#: Initiator Ready.
During PIPE# and SBA Operation: Not used while enqueueing requests via AGP SBA and
PIPE#, but used during the data phase of PIPE# and SBA transactions.
During FRAME# Operation: G_IRDY# is an output when GMCH acts as a FRAME#-based
AGP initiator and an input when the GMCH acts as a FRAME#- based AGP target. The assertion
of G_IRDY# indicates the current FRAME#-based AGP bus initiator's ability to complete the
current data phase of the transaction.
During Fast Write Operation: In Fast Write mode, G_IRDY# indicates that the AGP-compliant
master is ready to provide all write data for the current transaction. Once G_IRDY# is asserted
for a write operation, the master is not allowed to insert wait states. The master is never allowed
to insert a wait state during the initial data transfer (32 bytes) of a write transaction. However, it
may insert wait states after each 32-byte block is transferred.
G_TRDY#: Target Ready.
TRDY#
During PIPE# and SBA Operation: Not used while enqueueing requests via AGP SBA and
PIPE#, but used during the data phase of PIPE# and SBA transactions.
During FRAME# Operation: G_TRDY# is an input when the GMCH acts as an AGP initiator
and is an output when the GMCH acts as a FRAME#-based AGP target. The assertion of
G_TRDY# indicates the target's ability to complete the current data phase of the transaction.
During Fast Write Operation: In Fast Write mode, G_TRDY# indicates the AGP compliant
target is ready to receive write data for the entire transaction (when the transfer size is less than
or equal to 32 bytes) or is ready to transfer the initial or subsequent block (32 bytes) of data when
the transfer size is greater than 32 bytes. The target is allowed to insert wait states after each
block (32 bytes) is transferred on write transactions.
G_STOP#: Stop.
STOP#
During PIPE# and SBA Operation: This signal is not used during PIPE# or SBA operation.
During FRAME# Operation: G_STOP# is an input when the GMCH acts as a FRAME#-based
AGP initiator and is an output when the GMCH acts as a FRAME#- based AGP target.
G_STOP# is used for disconnect, retry, and abort sequences on the AGP interface.
DEVSEL# G_ DEVSEL#: Device Select.
During PIPE# and SBA Operation: This signal is not used during PIPE# or SBA operation.
During FRAME# Operation: G_DEVSEL#, when asserted, indicates that a FRAME#-based
AGP target device has decoded its address as the target of the current access. The GMCH
asserts G_DEVSEL# based on the DDR SDRAM address range being accessed by a PCI
initiator. As an input, G_DEVSEL# indicates whether the AGP master has recognized a PCI
cycle to it.
G_REQ#: Request.
REQ#
During SBA Operation: This signal is not used during SBA operation.
During PIPE# and FRAME# Operation: G_REQ#, when asserted, indicates that the AGP
master is requesting use of the AGP interface to run a FRAME#- or PIPE#-based operation.
GNT# G_GNT#: Grant.
During SBA, PIPE# and FRAME# Operation: G_GNT#, along with the information on the
ST[2:0] signals (status bus), indicates how the AGP interface will be used next. Refer to the AGP
Interface Specification, Revision 2.0 for further explanation of the ST[2:0] values and their
meanings.
AD[31:0] G_AD[31:0]: Address/Data Bus.
During PIPE# and FRAME# Operation: The G_AD[31:0] signals are used to transfer both
address and data information on the AGP interface.
During SBA Operation: The G_AD[31:0] signals are used to transfer data on the AGP interface.
886LCD-M Family
User Manual Date: 2010-06-22 Page 31 of 81
(continues)