Rock64 micro-sd controller defective?
Well. I looked into the boards schematics, rk805 and rk808 PMIC datasheets and it looks like on Rockpro64 it is theoretically possible to have voltage switching working. Because there SDMMC0 module is fed with LDO4 regulator of rk808 specifically, VCC_SDIO is provided through it. Nothing else is connected to it, so you can switch voltage safely. I guess. Big Grin I don't have this board anyway. Could anybody show numbers with UHS-I capable cards on Rockpro64?

With rock64, the situation is less clear and not this optimistic. rk805 is used as a PMIC, right? It has fewer LDOs/BUCKs and looking at the board schematics shows rather confusing results. There is a figure and table. In the figure, power domain of SDMMC0 is shown as VCCIO3 and it's listed among with VCCIO1 and VCC_PMU. Who knows is this just a conventional grouping for making it more readable or really this grouping has meaning. Because there are yet other groups and all of them are coming from VCC_IO, and it is sourced by BUCK4 of rk805. All of them are sourced from this regulator, that means, that switching voltage on BUCK4 will affect every of these domains. But in the table, the picture is a little bit different:
|IO power domain | IO voltage = 3.3V | IO voltage = 1.8V |
|VCCIO_PMU       |        3.3        |   not supported   |
|VCCIO1          |        3.3        |   not supported   |
|VCCIO2          |                   | 1.8 (default) eMMC|
|VCCIO3          |   3.3 (default)   |                   |
|VCCIO4          |   3.3 (default)   |                   |
|                |  WIFI:RTL8723BS   |                   |
|VCCIO5          |   3.3 (default)   |                   |
|VCCIO6          |   3.3 (default)   |                   |
So the question is what this table really shows? Empty cells left, do they mean that alternative voltage for the power domain is possible without affecting other ones? For example this table suggests, that I can switch VCCIO3, which is the SDMMC power domain, into 1.8V without affecting VCCIO1, for which 1.8V is not possible? And the voltage for VCCIO3 is 3.3V only as "default". Nothing says it can't be different. There is no "not supported" mark. But how is this possible? If all they are connected to the same BUCK4 regulator? This PMIC, rk805, is specifically designed for rk3328 (among another SoC), but it looks like they made it nearly impossible to provide a dedicated regulator for SDMMC0 power domain, that is allowed to switch voltage, without affecting other modules. And the same time they embedded a UHS-I capable controller inside of rk3328, that does require voltage switch for operating in this fast mode. Could anybody clarify this situation? What the above table does really tell? tllim please. Smile

Messages In This Thread
RE: Rock64 micro-sd controller defective? - by z4v4l - 11-23-2018, 06:30 PM

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