On Tue, Sep 20, 2016 at 10:10 AM, TsvetanUsunov <[email protected]> wrote: > > > понеделник, 19 септември 2016 г., 20:06:13 UTC+3, Hans de Goede написа: >> >> Hi, >> >> On 19-09-16 18:07, TsvetanUsunov 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. >> >> Ok, so what your suggesting is: >> >> axp803-ldo-io1 -\ >> [mux]---> mmc-supply >> Fixed-3.3v ------/ | >> | >> |mux-control >> A64 gpio out--------/ >> >> Note the above ascii-art requires a fixed-width font. >> >> With a pull-down (or pull-up) to fix the mux in a certain position when >> the gpio is in tri-state ? >> >> As long as we pin the axp803-ldo-io1 at 1.8v then the Linux regulator >> framework should be able to deal with, and in u-boot we can just >> keep things at 3.3v. >> >> > How would you suggest us to implement it? Will this additional GPIO >> > create troubles in eMMC driver philosophy? >> >> For the Linux mmc driver the mmc-supply is abstracted as a regulator, >> and the regulator framework should be able to deal with any setup >> you can come up with. >> >> > 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. >> >> As long as you default to 3.3v then the kernel's sd subsystem can >> dynamically switch voltage (through e.g. the gpio) if the card >> advertises it supports low voltage. Note that you're planning >> the first board to implement this that I know off, so the sunxi-mmc >> kernel driver will need some work to support voltage switching, >> but in the mean time things should work fine at 3.3v. >> >> > Also eMMC Flash and SDMMC card should be driven by separate voltages, as >> > they may work in any combinations. >> >> Ack, right, as said both cards should come up with 3.3v and then >> a new voltage will be negotiated before switching, so this definitely >> needs to be per card. >> >> > This means we need another AXP803 LDO and another GPIO for the SDMMC >> > card. >> >> Right > > > Micron eMMC chips we use do not support higher clock at lower voltage, so > the way we wired the schematic right now makes no much sense. > I check for other vendors but also can't find such eMMC chip, if someone > knows please let us know to investigate more? > > So in this case makes sense to move the dual voltage supply to the SD-MMC > card only but this rise some more issues :) > > The card is currently wired to port F which Vcc is internally connected > together with port B and H where is WiFi SIDO , I2C UARTs etc which will be > lost if we power with 1.8V, so no go. > > We can swap the SD-MMC and eMMC ports, port F and port C, but in this case > we will lose the NAND Flash option i.e. the possibility to run Android. > > I still can't find SD-MMC card which to work on 1.8 and 3.3V can you point > me to some model so we perform test and see if this is really good to have > feature, or we will cut this and wire 3.3V permanently :)
I have not tried low voltage SD Cards but... Here is a chart of the UHS modes http://panasonic.net/avc/sdcard/industrial_sd/performance.html Here are UHS SD Cards for sale: http://www.lexar.com/products.html I was unaware of 0.4V UHS-II, but Lexar is selling UHS-II cards. Don't know what supply voltage they need. ------------------------------------------------------- For eMMC I believe you are looking for: eMMC 4.5 HS200 eMMC 5.0 HS400 Kingston sells these, I think Samsung does too. http://www.kingston.com/us/embedded/emmc They come in wide temp https://media.kingston.com/pdfs/emmc/i_temp_eMMC_Product_Flyer.pdf About $5 for 4GB from US distributors, so probably $3 from Chinese one. Random check of similar Kingston part from Chinese supplier - $3.38 Support for HS200/HS400 is already in kernel so someone is using it. > > 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 [email protected]. > For more options, visit https://groups.google.com/d/optout. -- Jon Smirl [email protected] -- 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 [email protected]. For more options, visit https://groups.google.com/d/optout.
