On Mon, Sep 19, 2016 at 12:07 PM, TsvetanUsunov <tsvetanusu...@gmail.com> wrote: > Hi, > > We make our final touch of A64-OLinuXino PCB and there we add option eMMC > Flash to work on dual voltages 1.8V and 3.3V. > The eMMC is connected to AXP803 pin.34 GPIO1/LDO. The problem is that when > A64 boots and AXP803 is not initialized it outputs default 0.8V then after > initialization driver takes care to drive it 1.8V or 3.3V. > This makes impossible to boot from eMMC which is not good. We now think for > solution which to drive eMMC at 3.3V initially when AXP803 output is below > 1.8V but this adds unnecessary hardware complexity. > For hardware point of view it will be much more simplier if dedigated A64 > GPIO is used and initially is pulled down and after AXP803 is initialized is > pulled up. > How would you suggest us to implement it? Will this additional GPIO create > troubles in eMMC driver philosophy? > For the SDMMC we are still hesitating what to do as we don't know if the > card which will be inserted will support low voltage and higher speeds at > all. Also eMMC Flash and SDMMC card should be driven by separate voltages, > as they may work in any combinations. > This means we need another AXP803 LDO and another GPIO for the SDMMC card. > > By the way the current eMMC from Micron we use has 11MB Write speed no > matter what is the voltage and this is written in the datasheet, so maybe we > should switch and add this dual voltage to the SD MMC where someone could > use SD MMC card supporting higher clocks?
Does eMMC exist with the higher speed 1.8V option? I know some SD Cards support it. > > I would love to hear your opinion. > > Tsvetan > > -- > You received this message because you are subscribed to the Google Groups > "linux-sunxi" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to linux-sunxi+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. -- Jon Smirl jonsm...@gmail.com -- You received this message because you are subscribed to the Google Groups "linux-sunxi" group. To unsubscribe from this group and stop receiving emails from it, send an email to linux-sunxi+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
