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• Member since: August 27, 2007

My posting summary

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My comments

• Screen was full brightness, and always on.
  Peter,
  
  In the tests I sent you data on (and you based your blog posting on), we deliberately disabled any control of the screen brightness or turning off the screen when idle, and set the backlight to its highest brightness. I don't know about your conventional laptop, but mine certainly drops the brightness when put on battery; this was not done for our tests.
  
  We were/are interested in "worst case" numbers that could be intercompared with conventional laptop.
  
  We have a couple items left to do, probably a few weeks of implementation work:
  
  o fully power off the Geode's video and video drivers, which will save over 1/2 watt whenever the screen is inactive. We know the power savings due to a many channel meter hooked up to over 30 test points on the board; this is a major advantage we have in implementing our power management over most systems, which provide little if any help for instrumentation, and cause software to be working in the dark.
  o minor power savings from disabling the keyboard when in ebook mode.
  o tuning the knobs and dials of power management.
  
  At some later date, we expect the wireless firmware power consumption to also improve; but this is in Marvell's hands rather than ours.
  
  The code to use the DCON in the above power savings mode was mostly debugged in late June and awaits integration.
  
  Our major effort during July and some of August was ensuring the hardware works correctly in all respects, using the measurement setup described, that the hardware is ready for production; we now turn to finishing up, integrating and tuning the power management.
  
  Also note that many kids are taught out of doors in the developing world, and/or can only study out of doors. So this is very important in many parts of the world, even if unimportant in the United States. The OLPC is designed for those kids, not your use case. In reply to: "OLPC battery life: What's the real story?"

  August 29, 2007

  0 replies

• Ebook mode lifetime - > 13 hours.
  Yes, we are not finished with power management. There are several major power savings yet to be had, when running in typical operation.
  
  The major feature we have is the ability to read books (screen on, but processor suspended). In this mode with the screen on (something unlikely to be the case for any human I've ever seen). I have measured this at over 13 hours, occasionally flipping pages (the system wakes up extremely fast). In reply to: "OLPC battery life: What's the real story?"

  August 27, 2007

  1 reply