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Marco@fs
Mar 7th, 2013, 03:06 AM
hello,

is it possible to switch between the EBU and SDMMC-Card Interface at runtime because the PINs are chared?

That means, we would use the EBU (for: SDRAM, ethernet-chips) and SDCard via SDMMC-Interface (for save web-pages) in one Application.

Must i use multiplexers to disconnect the SDMMC-Card from bus?

nice greetings

Marco

Jackson
Mar 17th, 2013, 07:43 PM
Hi Marco,

It is generally difficult to use the same pin(s) for different functions in a design, as it is difficult to ensure that while the pin is used by one function it does not harm the other.
What may be possible is to “time multiplex” the function and use Pn_HWSEL to select/switch between the function.
The time multiplex method might work provided the two function are pretty much mutually exclusive, or you can accept an additional delay (switching between function).

Additionally, you will need some external multiplex logic to avoid both external components drive on the same pin at the same time.
Any operation with both devices active at the same time would consider highly critical.