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Multiple micro SD-Cards (SanDisk) on usdhc bus

Question asked by Walter Zimmer on Feb 21, 2019
Latest reply on Feb 21, 2019 by Kerry Zhou

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?

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