I have new idea how improve power consumption even more: add scaling for CVDD2 and PVDD1. We can set CVDD2 to low value when internal and external flash/SD at idle. Also we can set lower value for PVDD1 for lower volume.
So I have prepared new patch (hack
) and builds for tests.
So what expected?
1. Improved battery life - up to 30 hours playtime on mp3 on Clip Zip.
2. Minor improvements in audio quality at 0 dB, notable at <= -9 dB and major at > 0 dB (as with new settings clipping at high volume should be completely eliminated).
3. Freezes and bugs as always
1. Backlight of screen (on Clip Zip) changes brightness if flash/SD in usage and if you switch volume > 0 dB.
2. At this moment I test only DAC, so problems with ADC (recordings) or FM can be expected.
So what I want to know?
1. Is it works at all on others players? Write the name and variant (system > debug > view hw info) of your player and result.
2. If it works without big problems - try do battery runtime testing.http://knk.square7.ch/cvdd2/rocobox-cvdd2_scaling-0.patch
Builds with this patch + i2sout_without_dma.patch (http://forums.rockbox.org/index.php/topic,51184.0.html
P.S. Don't touch new settings in debug menu (*VDD*) if you not sure what you doing
PVDD1 derived from CVDD2.
PVDD1 used by digital part of DAC and ADC.
CVDD2 used by for flash, SD, RAM and probably OLED, some part of USB (and maybe something else). At now I can't set lower value for CVDD2 due internal flash instability. But I still hope to find solution and got 40 hours from Clip Zip at some day
AVDD17 derived from AVDD27.
AVDD17 used by analog part of DAC and ADC. Also used by others analog parts. If we rise it we got bigger maximum output volume. But at some point we got clipping. So I tune CVDD2, PVDD1 and AVDD17 for get maximum possible volume without clipping. Lower value of PVDD1 consume less power and slightly improving THD/IMD but at very low value we got clipping - so best value depend from volume.
All measurements (more than 100 measurements) was done with RMAA and Emu0204 with load 32 om.
I also checked again AUDIOSET2_HPH_QUALITY_HIGH + AUDIOSET3_HP_BIAS_150. It consume only 0.2 mA. At high volume (>= 0 dB) mostly no difference in audio quality. But if volume <= -9 dB we have notable improvement (THD better for 35%).