IDT PCI Bus Interface
PCI Transactions
79RC32438 User Reference Manual
10 - 17
November 4, 2002
Notes
Interrupts
In satellite mode, the RC32438 device does not provide any dedicated interrupt outputs. The PCI
messaging unit operates in both satellite and host modes. The PCI messaging unit interrupt output (i.e.,
PCIMUINTN) is a GPIO alternate function output (refer to Table 12.1 in Chapter 12). Although no GPIO pins
are dedicated for PCI interrupts, GPIO pins 29:26 have PCI buffers (refer to Table 1.3 in Chapter 1).
PCI Serial EEPROM Interface
When the RC32438 device is booted in PCI satellite mode with the execution of the CPU core
suspended, the PCI serial EEPROM is used to load PCI configuration registers whose addresses are less
than 0x80 in PCI configuration space. The PCI serial EEPROM interface provides a National Semicon-
ductor MICROWIRE compatible serial EEPROM interface. PCI Serial EEPROM done bit (EED) in the
PCIS register is set when the loading of configuration information has been completed and the Serial I/O
signals have been released. EEPROMs equal to or greater than 1024-bits in size should be used (0x80
corresponds to 128 8-bit registers).
Each EEPROM address corresponds to a 16-bit data quantity. This is in contrast to PCI configuration
which correspond to 8-bit quantities. For this reason, corresponding EEPROM addresses are equal to one
half of their PCI configuration space addresses. Unused EEPROM locations (i.e., those whose initial values
are don’t care) may be used to store application specific information. EEPROM addresses which are
greater than or equal to 0x40 in EEPROMs whose size is greater than 1024-bits may be used to store appli-
cation specific information. Application-specific information may be accessed from the EEPROM using the
SPI interface after the initialization process is completed.
For information on the operation of the PCI serial EEPROM I/O pins, see Chapter 16, Serial Peripheral
Interface.
PCI Transactions
Table 10.6 summarizes the PCI command codes supported by the PCI bus interface. The sections
following this table describe how these transactions are generated for master and target configurations.
PCIGNTN[0]
I
PCI Grant
. This signal is asserted by an external arbiter to indicate to
the RC32438 that access to the PCI bus has been granted. While PCIR-
STN is asserted, the RC32438 ignores the state of this signal.
PCIGNTN[1]
O
PCI EEPROM Chip Select
. In satellite mode this signal takes on the
alternate function of PCIEECS and is used as a PCI Serial EEPROM
chip select.
PCIGNTN[5:2]
O
Unused
. These signals are unused in this mode and driven high.
CBEN[3:0]
Command
IPBus
Master
DMA
Ch. 9 PCI
Master
DMA
Ch. 8 PCI
Master
PCI
Target
0000
Interrupt Acknowledge
No
No
No
Ignored
0001
Special Cycle
No
No
No
Ignored
0010
I/O Read
Yes
Yes
No
Yes
0011
I/O Write
Yes
No
Yes
Yes
0100
Reserved
No
No
No
Ignored
Table 10.6 Supported PCI Transactions (Part 1 of 2)
Pin Name
Type
Description
Table 10.5 PCI Arbitration Pin Functionality in PCI Satellite Mode (Part 2 of 2)