VIPER Technical Manual | Power and power management |
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Power management
All VIPER
To simplify the power consumption estimation of the VIPER, the following sections break down the process as follows:
•Processor383Hcurrent estimations, page 75384H.•Power385Hsavings, page 77386H.•External387Hperipheral device power estimations, page 78388H.•Power389Hestimate examples, page 79390H.The sections immediately following these detail the VIPER features that can be shutdown. See pages 81391Hto 84392H.
The section Processor393Hcurrent estimations, page 75394H, details current consumption of the VIPER for performance and power saving modes at different clock frequencies. Embedded Linux, Windows CE and VxWorks set up the PXA255 slightly differently:
•Embedded Linux and VxWorks are booted from Redboot, which sets up the PXA255 clock frequency to 100MHz (CCCR=0x121).
•Embedded Linux changes the Redboot setting to 400MHz in performance mode (CCCR=0x161).
•VxWorks makes no changes to the Redboot setting.•Windows CE sets up the PXA255 clock frequency to 400MHz in power saving mode (CCCR=0x241).
The section Power395Hsavings, page 77396H, only apples to Linux and VxWorks power estimation calculations, as Windows CE currently does not provide any power management support. This section shows potential power savings for that can be achieved by shutting down sections of the VIPER that are not required.
The section External397Hperipheral device power estimations, page 78398H, provides some examples of power consumption for various supported peripherals, such as LCD displays, CF and USB devices, which may or may not be used for your application.
The section Power399Hestimate examples, page 79400H, provides some examples to help you better understand how to use the information provided within the tables of the
Processor401Hcurrent estimations, Power402Hsavings and External403Hperipheral device power estimations sections.
© 2007 Eurotech Ltd Issue E | 74 |