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8M Mini SD Interface Questions

Question asked by adevries on Sep 27, 2019
Latest reply on Oct 2, 2019 by adevries

Hello Community,

 

I noticed that the 8M Mini DevBoard does not have any external pull-up resistors on its SD card interface. I thought that the SD specification requires that the data lines are pulled up to 1.8 or 3.3V? Are the data lines being pulled-up internally? And if so, how can the SD data lines be internally pulled up when the SD interface operates at 3.3V? It was my understanding that the i.MX 8M Mini cannot use internally pull-ups/pull-downs when the interface is running at 3.3V (due to Errata e50080).

 

Is it possible to use internal pull-up resistors when interfacing an 8M Mini with an SD card?
If I instead use external pull-ups, should the SD data lines be pulled up to NVCC_SD2?

Lastly, when the SD interface does a hardware reset (when the voltage to the SD card is turned off), are all the data lines, clock line, and command line also held low? Or do they remain high or clocking?

 

Thanks.

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