Motorola PowerQUICC II MPC8280 Series Reference Manual page 578

Communications Processor (CP)
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Not on the MPC8270 and the MPC8275.
14.3 Communications Processor (CP)
The communications processor (CP), also called the RISC microcontroller, is a 32-bit
controller for the CPM that resides on a separate bus from the core and, therefore, can
perform tasks independent of the G2_LE core. The CP handles lower-layer
communications tasks and DMA control, freeing the core to handle higher-layer activities.
The CP works with the peripheral controllers and parallel port to implement
user-programmable protocols and manage the serial DMA (SDMA) channels that transfer
data between the I/O channels and memory. It also manages the IDMA (independent DMA)
channels and contains an internal timer used to implement up to 16 additional software
timers.
The CP's architecture and instruction set are optimized for data communications and data
processing required by many wire-line and wireless communications standards.
14.3.1 CPM Performance Evaluation
Because the CP is a single shared resource used by all of the CPM's communications
peripherals, the combined service requests from all of the communications peripherals must
not exceed the CP's capacity. The amount of processing required by a particular
communications peripheral depends on the mode in which the peripheral is configured and
the maximum rate at which the channel requests service. To determine if CPM performance
and bus bandwidth consumption of a given configuration is valid, users should consult the
"MPC8280 CPM Performance Evaluator," which is located under "Application Software"
on a device's product page at www.motorola.com/semiconductors.
14.3.2 Features
The following is a list of the CP's important features.
• One system clock cycle per instruction
• 32-bit instruction object code
• Executes code from internal ROM or RAM
• 32-bit ALU data path
• 64-bit dual-port RAM access
• Optimized for communications processing
• Performs DMA bursting of serial data from/to dual-port RAM to/from external
memory. Note that IDMA cannot burst to dual-port RAM.
14-4
Freescale Semiconductor, Inc.
MPC8280 PowerQUICC II Family Reference Manual
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Go to: www.freescale.com
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