Motorola MPC8260 - Manual (Page 196)

5-12 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA
Part II. ConÞguration and Reset
In this system, the conÞguration master initially reads its own conÞguration word. It then
reads other conÞguration words and drives them to the conÞguration slaves by asserting
RSTCONF. As Figure 5-6 shows, this complex conÞguration is done without additional
glue logic. The conÞguration master controls the whole process by asserting the EPROM
control signals and the systemÕs address signals as needed.
5.4.2.4 Multiple MPC8260s in a System with No EPROM
In some cases, the conÞguration master capabilities of the MPC8260 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 MPC8260.
If this occurs, the user must do one of the following:
¥ Accept the default conÞguration,
¥ Emulate the conÞguration master actions in external logic (where the MPC8260 is
a conÞguration 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 conÞguration slave mode. For 1,024 clocks after PORESET negation, the
external hardware can conÞgure the different devices by driving appropriate
conÞguration words on the data bus and asserting RSTCONF for each device to
strobe the data being received.