Motorola MPC8260 - Manual (Page 80)

1-10 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA
Part I. Overview
1.6 MPC8260 ConÞgurations
The MPC8260 offers ßexibility in conÞguring the device for speciÞc applications. The
functions mentioned in the above sections are all available in the device, but not all of them
can be used at the same time. This does not imply that the device is not fully activated in
any given implementation: The CPM architecture has the advantage of using common
hardware resources for many different protocols, and applications. Two physical factors
limit the functionality in any given systemÑpinout and performance.
1.6.1 Pin ConÞgurations
Some pins have multiple functions. Choosing one function may preclude the use of another.
Information about multiplexing constraints can be found in Chapter
15, ÒCPM
Multiplexing,Ó and Chapter 35, ÒParallel I/O Ports.Ó
1.6.2 Serial Performance
Serial performance depends on a number of factors:
¥ Serial rate versus CPM clock frequency for adequate sampling on serial channels
¥ Serial rate and protocol versus CPM clock frequency for CP protocol handling
¥ Serial rate and protocol versus bus bandwidth
¥ Serial rate and protocol versus system core clock for adequate protocol handling
The second item above is addressed in this sectionÑthe CPÕs ability to handle high bit-rate
protocols in parallel. Slow bit-rate protocols do not signiÞcantly affect those numbers.
Table 1-2 describes a few options to conÞgure the fast communications channels on the
MPC8260. The frequency speciÞed is the minimum CPM frequency necessary to run the
mentioned protocols concurrently at full-duplex.
Table 1-2. MPC8260 Serial Performance
FCC1 FCC2 FCC3 MCC CPM Clock 60x Bus Clock
155-Mbps ATM 100 BaseT 100 BaseT 133 MHz 66 MHz
100 BaseT 100 BaseT 100 BaseT 133 MHz 66 MHz
155-Mbps ATM 128 * 64 Kbps channels 133 MHz 66 MHz
100 BaseT 100 BaseT 128 * 64 Kbps channels 133 MHz 66 MHz
155-Mbps ATM 256 * 64 Kbps channels 166 MHz 66 MHz
100 BaseT 256 * 64 Kbps channels 133 MHz 66 MHz
45-Mbps HDLC 256 * 64 Kbps 133 MHz 66 MHz
45-Mbps HDLC 100 BaseT 256 * 64 Kbps 166 MHz 66 MHz
100 BaseT 16 * 576 Kbps 166 MHz 66 MHz