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Rockbox mail archiveSubject: Power off testing - current and spinup timePower off testing - current and spinup time
From: Nuutti Kotivuori <naked_at_iki.fi>
Date: Wed, 04 Dec 2002 20:01:05 +0200 I did a few tests with the hard drive power-off toggle and this is what I came up with. My hard drive is: FUJITSU MHN2200AT. * Current These tests were made with bad equipment under bad circumstances - I can replicate the results easily, so they should have an internal consistency, but do not expect them to correlate to anybody else's test results :-) The unit is A, but it's not really relevant since the meter shows something way different. Playing, backlight off, HD off: 0.07 Playing, backlight on, HD off: 0.11 Playing, backlight off, HD sleep: 0.08 Playing, backlight on, HD sleep: 0.13 (all the rest are backlight off Booting up : 0.46 HD spun up and reading :~0.50 Spinning up peak power : 0.64 HD just before shutting down : 0.21 So, there is a difference between HD sleep and HD off. And that was basically what I wanted to know. * Timing Then I made some timing tests between hard drive power-off and sleep. Some of these are taken by hand, so they are not too reliable. ** Sleep In sleep mode, when ever the unit needs to read more, the hard drive led will light up, the drive will spin up, the led will flash a bit, and then go dark and the drive spins down again. Spin-up time given by firmware : constant 20ms There's gotta be a bug of some sort there, I could never see anything else in the timing by the firmware. Total time taken by one buffer fill : 3.1 s ** Power-off In power-off mode, the behaviour is a lot different. First the hard drive led will light up, then the drive will spin up - but it will take around 5 seconds for the drive to spin up. Then the led goes dark again for about a second. And after that it lights up again for a couple seconds or less. Spin-up time given by firmware (1) : 5100 ms Spin-up time given by firmware (2) : 1900 ms The first spin up time will show in the space between when the led goes dark - and the second time will show after the second read is finished. Then on to manual timings. Time taken by first spin-up : 5.3 s Delay between spin-ups : 2.2 s Time taken by second spin-up : 1.4 s Total time taken by one buffer fill : 8.9 s That last total time actually is taken from a separate timing, it just happens to hit exactly the same values. * Problems With the power-off enabled, all my 256-kbit MP3's were breaking up. Sometimes it was just a pause in playing, sometimes the sound stopped altogether and would not come back until after another buffer-fill. I had to increase the low-water mark considerably, to take into account the long spin-up times. That made performance relatively good, but there was one obvious difference. It might have been for the still inadequate low-water mark, but whenever I moved around with my player, the loading started to break up. When I was walking, I hardly ever heard any sound even. So it could be that the power-off spin-up is more easily disturbed by movement. * Conclusions I'm not sure what to make of all this, results are weird. But atleast right now, power-off is not for me. Because of the long spin-up time, the low-water mark problems and the relatively small power savings - it doesn't seem worth it. Hopefully this helps some. -- Naked Received on 2002-12-04 Page template was last modified "Tue Sep 7 00:00:02 2021" The Rockbox Crew -- Privacy Policy |