Configuring the ARM710T Header Card
3-6
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3.4
Setting the bus clocking mode
Switch S1 is used to select between asynchronous mode (STD) and Fastbus mode (FB).
The position of S1 is shown in Figure 1-1 on page 1-3.
Note
Do not change the setting of S1 while the processor is running.
Three bus clocking modes are supported by the processor. These are:
•
Asynchronous mode - the bus clock frequency is separate to the core clock
frequency.
•
Synchronous mode - the bus clock frequency is separate to the core clock
frequency, but the two are phase related. The core clock frequency is a multiple
of the bus clock frequency.
•
Fastbus mode - the core clock and the bus clock use the same clock. In this case
no setting-up is required for the header clock frequency.
Note
Synchronous clocking mode is not supported on this header card.
For more details of clocking modes see the ARM710T Datasheet.
