Freescale Semiconductor MPC8260 - Manual (Page 552)

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
Table 14-1. Possible PowerQUICC II Applications
Application MCC1
1
1
Not on the MPC8250 and the MPC8255.
MCC2 FCC1 FCC2
FCC3
2
2
Not on the MPC8255.
SCC1 SCC2 SCC3 SCC4 SMC1 SMC2
ISDN router 4 E1 4 E1 FEnet or ATM FEnet UART UART UART UART
ATM switch ATM FEnet UART
ATM access ATM FEnet FEnet
E3 or
E1’s
E3 or
E1’s
ATM UART
GSM mobile
switching center E1’s FEnet or ATM
Backbone 10 M
HDLC
10 M
HDLC