Filter
Top Products
VIPER Technical Manual Power and power management
© 2007 Eurotech Ltd Issue E 74
Power management
All VIPER power-down features and alteration of PXA255 operating frequency are fully
supported under Embedded Linux and VxWorks. Windows CE currently provides no
power management support.
To simplify the power consumption estimation of the VIPER, the following sections
break down the process as follows:
•
383HProcessor current estimations, page 384H75.
•
385HPower savings, page 386H77.
•
387HExternal peripheral device power estimations, page 388H78.
•
389HPower estimate examples, page 390H79.
The sections immediately following these detail the VIPER features that can be
shutdown. See pages
391H81 to 392H84.
The section
393HProcessor current estimations, page 394H75, 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
395HPower savings, page 396H77, 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
397HExternal peripheral device power estimations, page 398H78, 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
399HPower estimate examples, page 400H79, provides some examples to help you
better understand how to use the information provided within the tables of the
401HProcessor current estimations, 402HPower savings and 403HExternal peripheral device power
estimations
sections.