Support and General Use > Hardware
Sansа Clip Zip - Improve battery life
Mihail Zenkov:
--- Quote from: saratoga on September 27, 2014, 05:42:51 PM ---Do you know how much of the change is from the voltage settings and how much is from the CPU frequency?
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I check on playing flac:
mod PLLA save 3.5 mA
mod CVDD1 save 2.2 mA
mod CVDD2 save 1 mA
mod PVDD1 save 1 mA
--- Quote from: saratoga on September 27, 2014, 05:42:51 PM ---Or is it that lower clock means you can more safely use a lower voltage?
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Yes, it also allows use lower voltage.
--- Quote from: saratoga on September 27, 2014, 05:42:51 PM ---We did a lot of testing years ago, I will try to find the results and forward them to you. I found that increasing PCLK (the memory bus is on this) greatly increased performance but also power draw. At lower speeds, the player was slower, but more efficient. Running the memory faster massively improved how fast some of the decoders were (far fewer MHz needed for realtime playback) but decreased battery anyway.
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I try check PCLK. Any idea what also I should check?
I try change PVDD2 and have worst result, even if I try disable it (write 0x80 to it).
--- Quote from: saratoga on September 27, 2014, 06:29:37 PM ---Note that I changed the backlight current sink on value to be 91 (its previous value) rather than 90. Probably doesn't matter but I was unclear on why it was changed.
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As datasheet say it shouldn't change any thing. Clip Plus and Clip v2 set it to 0x90. I set it to 0x90 and don't see any changes. I think 0x91 just mistake.
--- Quote from: saratoga on September 27, 2014, 06:47:39 PM ---1) Reducing the main CPU frequency is fine for FLAC and for people who don't use much DSP effects, but probably even mp3 + EQ would skip that low.
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Right, we need dynamically scaling. But it more complicated to test and tune.
--- Quote from: saratoga on September 27, 2014, 06:47:39 PM ---2) If you change any of the registers related to supply voltages, make sure that you don't reduce the device's maximum volume. 0dB should be the max without distortion if the audio hardware has the correct voltages.
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Ok. You already have this problem with a patch?
--- Quote from: saratoga on September 28, 2014, 12:36:00 AM ---Patch with work in progress frequency scaling: http://www.rockbox.org/tracker/task/11297
As you can see we never figured out why dynamically scaling the frequency reduced battery life. Possibly this was a mistake or oversight if you found that lowering the clock improved battery life.
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I try check it.
My first patch have problem - it change core voltage in bootloader, fixed in new version.
I also think we should set CPUFREQ_DEFAULTA and CPUFREQ_NORMAL to FCLK, as we don't have dynamically frequency scaling. With current value we have wrong udelay.
Mihail Zenkov:
I check PCLK - try 12MHz and 6Mhz - no significant difference.
saratoga:
I think that is too low. The maximum is 60MHz, and we found acceptable performance down to about 20MHz (lowering it too much means the CPU wastes a lot of power waiting for memory loadds).
By the way, can you join use in #rockbox? We are discussing these patches.
Edit: Testing the USB and backlight changes increased my Zip runtime by 32%.
saratoga:
To help with testing, I've added new debug menus that show the current SOC voltage regulator outputs (using an on board A/D to read the voltages). You can see then under System -> debug -> view io ports and then hit the down button to scroll through all the voltages.
Mihail Zenkov:
--- Quote from: saratoga on September 28, 2014, 01:45:04 PM ---I think that is too low. The maximum is 60MHz, and we found acceptable performance down to about 20MHz (lowering it too much means the CPU wastes a lot of power waiting for memory loadds).
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I just test it. In patch I don't change it (24Mhz).
--- Quote from: saratoga on September 28, 2014, 01:45:04 PM ---By the way, can you join use in #rockbox? We are discussing these patches.
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I don't use IRC, sorry.
--- Quote from: saratoga on September 28, 2014, 01:45:04 PM ---Edit: Testing the USB and backlight changes increased my Zip runtime by 32%.
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Good.
--- Quote from: saratoga on September 28, 2014, 03:38:26 PM ---To help with testing, I've added new debug menus that show the current SOC voltage regulator outputs (using an on board A/D to read the voltages). You can see then under System -> debug -> view io ports and then hit the down button to scroll through all the voltages.
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Great! What I want add today :)
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