Proprietary and Confidential to PMC-Sierra, Inc and for its Customers
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Internal Use
Document ID: PMC-2010146, Issue 4
49
PM2329 ClassiPI Network Classification Processor Datasheet
2.4.1.5 32-Bit Mode
When the SDWIDTH64 pin is tied low during reset, the system interface is configured to work in 32-bit
mode. In this case, all data transfer takes place over SD[63:32] only, and SA[2] must be connected to
address bit 2 of the external processor (the PM2329 interprets it as SA[2]).
2.4.1.6 Byte Ordering
PM2329 byte organization convention assumes that lower addresses contain the more significant bytes.
For example, 32-bit mode, the MSB lies at address 0 and is passed on SD [63:56], while the LSB lies at
address 3 and is passed over SD [39:32].
2.4.1.7 Cascade Mode Addressing
All the SA[15:3] address lines, and the SCE0*, SCE1*, and SCE2 signals, are connected in parallel to the
corresponding pins of all PM2329 devices in the cascade.
When the processor accesses the PM2329 register space with SA[15] = 0, each device in the cascade will
compare address lines SA[14:12] against the assigned Cascade ID (CID#) of the device. Access to a
particular device in the cascade will be enabled if SA[14:12] matches the CID# of that device.
When the processor accesses the PM2329 register space with SA[15] equal to 1, SA[14:12] lines are
ignored and cascade bus mechanism determines the device that responds to the access.
2.4.1.8 Local and Global Register Access
The PM2329 register space supports two access mechanisms: Local and Global. Some registers are
accessed in Local access mode while others are accessible via Glocal access mode.
This access mechanism permits all system interface signals of the devices in the cascade (except SINT*) to
be wired in parallel to the system bus, including the SCE0*, SCE1* and SCE2 system chip enable signals.
While all devices in the cascade are selected by the processor at the same time (since all system chip
enables are simultaneously asserted active to all devices), arbitration logic inside the PM2329 devices
ensure that only one of them will respond during processor read cycles. Only the primary device
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s SINT*
is tied to the processor; all other SINT* signals are left unconnected.
For Local access, the following conditions must be met:
SA[15] should be driven to 0,
SA[14:12] must match the assigned CID# of the device, and
The lower SA signals must specify the address of the desired register.
Reads or Writes to the individual registers accessible via Local access mechanism can be performed this
way in both non-cascaded or cascaded configurations.
Table 15
System Bus 32-bit
System Data Bus (SD)
47:40
39:32
2
3
Bit Range
Byte Address
63:56
0
55:46
1
31:24
na
23:16
na
15:8
na
7:0
na