Freescale Semiconductor MPC8260 - Manual (Page 107)

Overview
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
Freescale Semiconductor 1-13
1.6 PowerQUICC II Configurations
The PowerQUICC II offers flexibility in configuring the device for specific 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 system—pinout and performance.
1.6.1 Pin Configurations
Some pins have multiple functions. Choosing one function may preclude the use of another. Information
about multiplexing constraints can be found in
Chapter 16, “CPM Multiplexing,” and Chapter 40,
“Parallel I/O Ports.”
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 section—the CP’s ability to handle high bit-rate protocols in
parallel. Slow bit-rate protocols do not significantly affect those numbers.
Table 1-2 describes a few options to configure the fast communications channels on the PowerQUICC II.
The frequency specified is the minimum CPM frequency necessary to run the mentioned protocols
concurrently at full-duplex.
Table 1-2. Serial Performance
1
1
For all PowerQUICC II devices, except for the MPC8250 (see Table 1-3 ).
FCC1 FCC2 FCC3
2
2 Not on the MPC8255.
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