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ARCHITECTURAL OVERVIEW
S5933
THE S5933 PCI CONTROLLER
AMCC’s S5933 is a powerful and flexible PCI control-
ler supporting several levels of interface sophistica-
tion. At the lowest level, it can serve simply as a PCI
bus target with modest transfer requirements (since
the PCI bus “plug-and-play” architecture is a benefit
even when the transfer rate demand is low). For
high-performance applications, the S5933 can be-
come the bus master and can attain the peak transfer
capabilities of 132 MByte/sec with a 32-bit PCI bus.
FUNCTIONAL ELEMENTS
The block diagram in Figure 1 shows the major func-
tional elements within the S5933. The S5933 pro-
vides three physical bus interfaces: the PCI bus, the
Add-On bus, and an optional external non-volatile
memory. Data movement can occur between the PCI
bus and the Add-On bus or the PCI bus and the non-
volatile memory. Transfers between PCI and Add-On
buses can take place through the mailbox registers or
the FIFOs, or can make use of the Pass-Thru data
path. FIFO transfers on the PCI bus interface can be
performed either through software control or through
hardware (using the S5933 as bus master).
MAILBOXES
The mailbox registers (shown in Figure 2) of the
S5933 provide a bidirectional data path that can be
used to send data or software control information be-
tween the system platform and the Add-On product.
These mailboxes are intended to serve as
customizable command, status, and parametric data
registers. Use of the mailbox registers is defined by
an application’s own software; they are often used to
initiate larger data transfers over either the FIFO or
Pass-Thru data paths. Interrupts can be configured to
occur on the PCI and Add-On bus (if desired) based
on a specific mailbox event(s).
Figure 2. Mailbox Register Concept
PCI
"OUTGOING"
MAILBOXES
PCI
"INCOMING"
MAILBOXES
ADD-ON
"INCOMING"
MAILBOXES
ADD-ON
"OUTGOING"
MAILBOXES
ADD-ON
INTERRUPT
IF
PCI WRITE
PCI
INTERRUPT
IF
ADD-ON READ
EMPTY/FULL
LOGIC
32
ADD-ON
PCI
MAILBOXES
16 BYTES TOTAL
PCI
INTERRUPT
IF
ADD-ON
WRITE
ADD-ON
INTERRUPT
IF
PCI READ
PCI
ADD-ON
MAILBOXES
16 BYTES TOTAL
EMPTY/FULL
LOGIC
32
PCI
BUS
INTERFACE
ADD-ON
INTERFACE