ARM ARM710T, Руководство пользователя

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Configuring the ARM710T Header Card
3-6 © Copyright ARM Limited 1999. All rights reserved. ARM DUI 0114A
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.