Multiple micro SD-Cards (SanDisk) on usdhc bus

walterzimmer — Thu, 21 Feb 2019 09:41:30 GMT

I like to increase Disk storage by adding multiple micro SD Cards onto a single SDHC bus (MK66FX1M0 and IMXRT1052).

NO SPI with separated CS but single SDHC bus

Can it be done?

How is it done HW and SW wise?

II test with MK66, where I added 2 microSD cards using SD card adapter.

All signals are in parallel.

I read that CMD2 and CMD3 have to be repeated until no card responds and each card that responded to CMD2 should go to inactive state.

However, it seams that only one card is responding continuously changing the suggested RCA

(e.g. when I cycle 6 times CMD2/CMD3 - with 2 cards - I get RCA of 'AAAA', 'AAAB', 'AAAC', 'AAAD', 'AAAE', 'AAAF'

Any suggestion on HW and SW?

Re: Multiple micro SD-Cards (SanDisk) on usdhc bus

kerryzhou — Fri, 22 Feb 2019 06:13:22 GMT

Hi Walter Zimmer,

MK66 just have one SDHC module, so you just can add one SD card.

If you want to add the other SD card in the K66, you need to use the SPI interface.

From my viewpoint, you can't use two SD card in parallel with the same SDHC interface.

You can try the sd card on your side, if each SD card works alone, but two sd cards can't work together, it will also demonstrate that theory.

About the SD card code for K66, you can refer to the SDK code, which can be downloaded from this link:

Welcome | MCUXpresso SDK Builder

Select the FRDM-K66 board, then generate the code, and download it.

You can find the SD code from this folder:

SDK_2.5.0_FRDM-K66F\boards\frdmk66f\driver_examples\sdcard

Wish it helps you!

If you still have question about it, please kindly let me know.

Have a great day,
Kerry

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topic Re: Multiple micro SD-Cards (SanDisk) on usdhc bus in Kinetis Microcontrollers

Multiple micro SD-Cards (SanDisk) on usdhc bus

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