External Signal Description
MCF548x Reference Manual, Rev. 3
Freescale Semiconductor 19-3
19.2.3 Device Select (PCIDEVSEL)
The PCIDEVSEL signal is asserted active low when the PCI controller decodes that it is the target of a
PCI transaction from the address presented on the PCI bus during the address phase.
19.2.4 Frame (PCIFRAME)
The PCIFRAME signal is asserted active low by a PCI initiator to indicate the beginning of a transaction.
It is deasserted when the initiator is ready to complete the final data phase.
19.2.5 Initialization Device Select (PCIIDSEL)
The PCIIDSEL signal is asserted active high during a PCI Type 0 Configuration Cycle to address the PCI
Configuration header.
19.2.6 Initiator Ready (PCIIRDY)
The PCIIRDY signal is asserted active low to indicate that the PCI initiator is ready to transfer data. During
a write operation, assertion indicates that the master is driving valid data on the bus. During a read
operation, assertion indicates that the master is ready to accept data.
19.2.7 Parity (PCIPAR)
The PCIPAR signal indicates the parity on the PCIAD[31:0] and PCICXBE[3:0] lines.
19.2.8 PCI Clock (CLKIN)
The CLKIN signal serves as a reference clock for generation of the internal PCI clock. For more
information, see Section 19.4.7, “PCI Clock Scheme.”
19.2.9 Parity Error (PCIPERR)
The PCIPERR signal is asserted active low when a data phase parity error is detected if enabled.
19.2.10 Reset (PCIRESET)
The PCIRESET signal is asserted active low by the PCI controller to reset the PCI bus. This signal is
asserted after MCF548x reset and must be negated to enable usage of the PCI bus.
19.2.11 System Error (PCISERR)
The PCISERR signal, if enabled, is asserted active low when an address phase parity error is detected.
19.2.12 Stop (PCISTOP)
The PCISTOP signal is asserted active low by the currently addressed target to indicate that it wishes to
stop the current transaction.