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Topic: How to interface microSD or SD card to USB / microUSB directly ? (Read 11822 times) previous topic - next topic

damalex

I want to interface a microSD card within a card socket directly to microUSB. But I am confused with the D+ , D- pins of the USB and the RSV pin of the microSD card socket.

After some research I also found out speed depends on resistor pulling also.
It would be helpful if somebody address this issue too.

Also state if it is not possible without the aid of some logic chip.(state the cheapest possible chip , if yes )

An early reply would be appreciated.
I thank you for your time and generosity.

I have uploaded a base Eagle Schematic. It would be MOST helpful if anyone makes the connections in it instead of answering a long paragraph( also time saving for you people !!!)

krupski


It would be MOST helpful if anyone makes the connections in it instead of answering a long paragraph( also time saving for you people !!!)


Simple answer: You can't. USB is an interface and a communications protocol.

SD cards are simply "address, then read or write".

They're not compatible I/O voltage-wise, nor are they compatible communication protocol-wise.
Gentlemen may prefer Blondes, but Real Men prefer Redheads!

krupski


Also state if it is not possible without the aid of some logic chip.(state the cheapest possible chip , if yes )


This: https://www.ghielectronics.com/catalog/product/337 is a neat board that may help you out......?
Gentlemen may prefer Blondes, but Real Men prefer Redheads!

damalex

I have an Atmel 1280 chip (that I can program via AVR programmer) , an SD card socket breakout board , a microUSB breakout  board .I  DONT have Atmega 16u2 or FTDI serial to TTL logic chip.

Can I interface my SD card to the microUSB via the AVR chip so that it will behave as an ordinary USB card reader when connected to computer.(ie. I can view it in my file manager , perform copy paste operations etc)?

If yes , it would be very helpful if anyone could share some demo code.

Thank You

Zapro


Can I interface my SD card to the microUSB via the AVR chip so that it will behave as an ordinary USB card reader when connected to computer.(ie. I can view it in my file manager , perform copy paste operations etc)?


No. Absolutely impossible. Get a card reader - they are a few $ a piece.

// Per.

fungus


I have an Atmel 1280 chip (that I can program via AVR programmer) , an SD card socket breakout board , a microUSB breakout  board .I  DONT have Atmega 16u2 or FTDI serial to TTL logic chip.

Can I interface my SD card to the microUSB via the AVR chip so that it will behave as an ordinary USB card reader when connected to computer.(ie. I can view it in my file manager , perform copy paste operations etc)?


In theory, yes! (of course!)

But why would you want to use an expensive chip and spend weeks getting it to work when it's a solved problem and SD-to-USB adapters cost $1?

http://www.ebay.com/sch/i.html?_nkw=usb+sd+card+reader
Advanced Arduino

damalex

#6
Mar 18, 2014, 04:07 pm Last Edit: Mar 18, 2014, 05:24 pm by damalex Reason: 1
Quote
But why would you want to use an expensive chip and spend weeks getting it to work when it's a solved problem and SD-to-USB adapters cost $1?


Actually its the part of a project in which I have to get the microSD card working as simply by putting the USB plug in.
Kind of like the mobile phones.I have to keep the cost as minimal as possible for the project to be successful.But the FTDI FT232RL is such an expensive chip !!!  =(

Finally I researched for a while and come up with FTDI FT230XS as the interfacing chip ( if you know any cheaper chip , please do tell !!!)
Also there is another FT221XS that seems to do the job.

Can I use this chip instead ? It would be helpful is somebody makes the connections in the Eagle schematic .

I have no knowledge in USB to UART interfacing (as you can see from the questions posted above ) and terms like DTR pin is confusing to me .

#Additional info:The project operates at 3.3V .

#What I want : When USB cable is plugged in from computer to the project I want the microSD card to be seen from the computer as an USB card reader would have.

#Problem: I want the interfacing to be as cheap as possible.


Thank You for your time

Zapro


jensvanhoof

Check this post from last week:

http://forum.arduino.cc/index.php?topic=225376.0

I was trying to do basically the same thing, using the VUB300 chip from Saelig.

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