SD card to USB

Hi friends,

Can somebody please tell me how to connect SD card directly to usb cable 4 pin ( direct ).

Hopefully awaiting an answer...
Thank u.

Hi friends,

Can somebody please tell me how to connect SD card directly to usb cable 4 pin ( direct ).

Hopefully awaiting an answer...
Thank u.

Bare all the wires,
Solder all the wires together,
The Electrons are smart enough to figure out the correct path to accomplish your mission.

All Connected.
Mission Accomplished!

Now, if you want to access the data from a SDCard by connecting it to a USB port, you are going to need hardware.

The electrical interface of a USB port(cable) and an SDcard are NOT directly COMPATIBLE.

So, in answer to your question, there is NO way to DIRECTLY WIRE a USB cable to a SDcard.


This is the question I've been presented with, too.

Currently, I have a Catalex microSD Card module that interfaces beautifully with my Arduino Nano v3 over SPI. However, my users have shown me that it'd be too much of a pain to disconnect my device and remove the cover to access the SD card so they can plug it into the computer.

Ideally, they want a way to easily interface with the PC/Mac; USB is preferred.

I can't seem to find a decent explanation or tutorial to point me in the right direction. I'd love to just solder a USB-B header to my board, and couple resistors/ICs so that the PC/Mac can interface with the SD card when the device is off, and the Arduino reads the SD card when the device is on.

(If I have to design my own SD card setup to do have the SD socket and additional ICs to interface with both Arduino and computer, that'd be fine, too.)

If any information could be provided to at least point me in the right direction, I'd be greatly appreciate.

Thanks in advance,

VUB 3000, lets PC or Arduino control the SD card. That and some buffering to let one side or the manage the signal lines.
I have been working on a design for a card/shield to allow that, see datasheet and attached schematic.

One issue is that Arduino talks to the SD card in Serial mode (SPI) while PC talks to the card in parallel/4-bit data mode, and the card has to be reset in between modes.

VUB300 Datasheet-v14.pdf (406 KB)

WOWZERS. That's not nearly as straightforward (nor cheap) as I thought possible, but I appreciate the fast reply and info.

Just out of curiosity, how does something as small as this work? I use it at home and my PC sees it as an external device almost immediately:

Reading some of the older threads makes me keen on the idea of using the Nano's USB port. Hook it up to the PC/Mac using a USB cable, let the computer see it as a serial device, then handle that in my sketch. My understanding is that I could run it at 9600 baud. I should have no more than 800 files, ranging in size from 3 - 40 bytes. I'm not concerned about speed. Sound legit?

I'm writing my own PC/Mac software for this, so it would know how to read/send the data. The only thing I'm concerned about is the fact that my device has MIDI. How do I NOT interfere with my RX0 and TX1 between MIDI and the computer?

Finally, would it be possible to use a USB-B header and tie into the Arduino so that the header is external of my enclosure? Perhaps use something like the FT232R to tie into RX0 and TX1?

Lots of questions, I know. (I count 5.)

I believe you would need a separate USB from the USB going to the FT232 that's on the Nano.

The design is still a work in progress, no software written yet.

Right. My own USB-B jack, soldered to my own PCB, going into my own FT232R (also soldered to my own PCB), which then ties to the Arduino's serial RX/TX. Let's skip the Nano's USB jack.

Great... now I need an FT232R chip. :slight_smile: And I think I read some decoupling caps.

What does a 2nd USB in parallel with the first one get you? Besides interference from the PC?

I can't see what "this" is in reply #4, but if it's an SD card reader connected via USB to a PC, then it has a similar kind of chip as the VUB3000 to handle the USB serial data (single direction data+clock line over twisted pair) into 0/5V levels (0/3.3V?) that other devices like SD card need, with SD card using a 4-bit parallel interface with clock & chip select for speed. Maybe even use the mechanical Card Detect and Write Protect feature of a card or socket.

I can't see what "this" is in reply #4

It's a Kingston microSD card reader.

I just took mine apart at home and am very impressed by the size (10mm x 20mm). The U1 is black goop, so I have no idea what it is.

What does a 2nd USB in parallel with the first one get you? Besides interference from the PC?

Only one thing: easy access from the outside of the enclosure. I don't know if I can redesign my PCB to rotate the Arduino. (Just looked at it; yeah, I can't redesign the PCB.)

I wonder if I could make some kind of "jumper"?