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[PIC] Interfacing between USB and SD card voltage levels

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Venkadesh_M

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Hello All, I want to interface between MMC card and USB pen drive with a PIC 16F controller. My problem is voltage level two devices, USB has 5V logic and SD card operates on 3.3V, So how can I do this with out voltage level convertors or anything else am I missing?

I am New to USB, So please give me if you have any sample code for USB interfacing.

Thanks In Advance !!
 

FvM

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Interface voltage levels is a minor problem. The USB data lines are usually interfaced with a 3.3V supplied driver, 5V processors have an internal 3.3V regultor for this purpose.

To interface a USB pen drive, you need an interface with host/OTG functionaility. PIC16 or PIC18 don't have it. Starting with PIC24.

There's a complete collection of USB and SD card projects in the Microchip Application Libarary, e.g. datalogger on USB pen drive etc.
 

Venkadesh_M

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The USB data lines are usually interfaced with a 3.3V supplied driver, 5V processors have an internal 3.3V regultor for this purpose.

Sorry I couldn't get it, Please Can you explain further ?

Do you mean Vbus only needs 4.5 to 5.5V but the D lines need only 3.3V for logic ?
 
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FvM

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Do you mean Vbus only needs 4.5 to 5.5V but the D lines need only 3.3V for logic ?
Yes. Review USB spec or datasheet of USB PIC...
 

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