Communications Processor Module Overview
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
14-4 Freescale Semiconductor
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
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 “MPC8260 CPM Performance Evaluator,” which is located under “Application
Software” on a device’s product page at www.freescale.com.

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
Table14-1. Possible PowerQUICC II Applications
Application MCC11
1Not on the MPC8250 and the MPC8255.
MCC2 FCC1 FCC2 FCC3
2
2Not on the MPC8255.
SCC1 SCC2 SCC3 SCC4 SMC1 SMC2
ISDN router 4 E1 4 E1 FEnet or ATM FEnet UART UART UART UART
ATM s wi tc h ATM FEn et UAR T
ATM a cc e ss ATM FEn et FEne t
E3 or
E1’s
E3 or
E1’s
ATM UAR T
GSM mobile
switching center
E1’s FEnet or ATM
Backbone
10 M
HDLC
10 M
HDLC