MPC8280 datasheet(237/1386 Pages) FREESCALE

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MPC8280 PowerQUICC II Family Reference Manual, Rev. 1

Freescale Semiconductor

5-13

In this system, the configuration master initially reads its own configuration word. It then reads other

configuration words and drives them to the configuration slaves by asserting RSTCONF. As Figure 5-7

shows, this complex configuration is done without additional glue logic. The configuration master controls

the whole process by asserting the EPROM control signals and the system’s address signals as needed.

5.4.2.4

Multiple MPC8280s in a System with No EPROM

In some cases, the configuration master capabilities of the MPC8280 cannot be used. This can happen for

example if there is no boot EPROM in the system or the boot EPROM is not controlled by an MPC8280.

If this occurs, the user must do one of the following:

•

Accept the default configuration,

•

Emulate the configuration master actions in external logic (where the MPC8280 is a configuration

slave).

•

The external hardware should be connected to all RSTCONF pins of the different devices and to

the upper 32 bits of the data bus. During PORESET, the rising edge the external hardware should

negate all RSTCONF inputs to put all of the devices in their configuration slave mode. For 1,024

clocks after PORESET negation, the external hardware can configure the different devices by

driving appropriate configuration words on the data bus and asserting RSTCONF for each device

to strobe the data being received.

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