Hello,
I have a situation where I must access storage media from another system, which is also being written to constantly. I was thinking about using SDIO for this, but there is only one of these peripherals on each system. For this reason it makes sense to multiplex two identical SD/eMMC devices and switch them out quickly to allow the the i.MX8M system to copy a chunk of data from one device, while the other writes the next chunk of data to the other.
However, I need to understand what the limitations of the i.MX8M Mini to determine if this will work.
If anyone has another suggested approach for this problem I'd also be interested to hear it.
Hi Craig
>1.What determines the SD card powering/mounting process?
>2.Can how SD cards are powered up/mounted be changed?
seems only limitation on such configuration is power-up sequence described in
sect.3.2.1 Power-up sequence i.MX 8M Mini Applications Processor Datasheet for Consumer Products
>3.Can the speed of SDIO be changed?
I am afraid not, as speed is defined automatically in SD driver when it reads SD capability register.
>4.Can I use SPI to access SD card data?
no.
Best regards
igor
Hi Igor, thanks for your reply.
In table 30 of this document it talks about low speed/full speed/high speed mode (400KHz/25MHz/50MHz). What determines which clock frequency is used? And what is the default/max SDIO clock frequency?
Thanks,
Craig
>What determines which clock frequency is used?
driver reads CSD register of SD card and sets frequency accordingly.
Details can be found in SD specification on
https://www.sdcard.org/downloads/pls/
Best regards
igor