01-18-2018, 06:08 AM
Can you please calm down and just have a look at the schematics for Rock64... the SD-Card interface has a fixed 3.3V supply, so it will only support 3.3V modes, the eMMC has a fixed 1.8V supply, so it will support 3.3V and 1.8V modes (the lower speed modes also work on 1.8V). To support dual voltage modes, you need hardware support for dynamic adjustment of VCC_IO which is not trivial to implement for u-boot and Linux which is why you don't see that configuration a lot on single board computers...
Come have a chat in the Pine IRC channel >>