01-18-2018, 05:10 PM
again and again...
voltage level of the I/O lines to the card is driven by the host controller. HC supporting UHS-I modes has the ability to switch voltage of I/O signals to the card. Its I/O cells voltage supply should be capable of 1.8-3.3V range. what you show is not a voltage supply for SDMMC interface on the SoC, it's the same reference to the TF card cage. and then again, if HC's I/O cells are powered 3.3V only, then the question is why so, if the interface is capable of supporting high speed modes, synthetically cut of this possibility not providing a proper power supply to it?
since, it seems, nobody does really care, it's better to stay with 20 MB/s. A user has bought a bunch of not exactly cheap UHS-I SD cards in the hope to use them with the board, but let's direct him to buy even more expensive eMMC module! after all it's faster! Or let him buy an SSD and plug it into USB3.
voltage level of the I/O lines to the card is driven by the host controller. HC supporting UHS-I modes has the ability to switch voltage of I/O signals to the card. Its I/O cells voltage supply should be capable of 1.8-3.3V range. what you show is not a voltage supply for SDMMC interface on the SoC, it's the same reference to the TF card cage. and then again, if HC's I/O cells are powered 3.3V only, then the question is why so, if the interface is capable of supporting high speed modes, synthetically cut of this possibility not providing a proper power supply to it?
since, it seems, nobody does really care, it's better to stay with 20 MB/s. A user has bought a bunch of not exactly cheap UHS-I SD cards in the hope to use them with the board, but let's direct him to buy even more expensive eMMC module! after all it's faster! Or let him buy an SSD and plug it into USB3.
ANT - my hobby OS for x86 and ARM.
