PCI Bus Controller
22-4
Freescale Semiconductor
22.2.4
Device Select (PCI_DEVSEL)
The PCI_DEVSEL signal asserts active low when the PCI controller decodes it is the target of a PCI
transaction from the address presented on the PCI bus during the address phase.
22.2.5
Frame (PCI_FRAME
)
The PCI_FRAME signal asserts active low by a PCI initiator to indicate the beginning of a transaction. It
deasserts when the initiator can complete the final data phase.
22.2.6
Grant (PCI_GNT[3:0])
The PCI_GNT[3:0] signals assert to external masters to give them control of the PCI bus. When the PCI
arbiter module is disabled, PCI_GNT[0] operates as the request output of the PCI controller and
PCI_GNT[3:1] is statically driven high.
22.2.7
Initialization Device Select (PCI_IDSEL)
The PCI_IDSEL signal asserts active high during a PCI Type 0 configuration cycle to address the PCI
configuration header.
22.2.8
Interrupt (PCI_INTA)
The PCI_INTA signal asserts active low by the PCI controller to request an interrupt.
22.2.9
Initiator Ready (PCI_IRDY
)
The PCI_IRDY signal is asserted active low to indicate that the PCI initiator can transfer data. During a
write operation, assertion indicates the master is driving valid data on the bus. During a read operation,
assertion indicates the master can accept data.
22.2.10 Parity (PCI_PAR)
The PCI_PAR signal indicates the parity on the PCI_AD[31:0] and PCI_CBE[3:0] lines.
22.2.11 Parity Error (PCI_PERR)
If enabled, the PCI_PERR signal asserts active low when a data phase parity error is detected.
22.2.12 Request (PCI_REQ[3:0])
The PCI_REQ[3:0] signals assert by external PCI masters when they require access to the PCI bus. When
the internal PCI arbiter module is disabled, PCI_REQ[0] is the grant input for the PCI controller. It is
driven by an external PCI arbiter.
Содержание MCF54455
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