I have this PCB SD card reader:

Enter image description here

The pins are GND, 3V3, 5V, CS, MOSI, SCK, MISO, GND.

How do I interface it with something else? Is it possible to wire these pins to a USB plug? How? Or another interface?

  • Can the downvoter explain how I can improve the question or why it is bad?
    – Basj
    Mar 29, 2015 at 20:39

1 Answer 1


Depends on what your end goal is.

Such a PCB is most likely designed to be used with, say, a microcontroller - for example those used by Arduino's, mBeds, etc.

You couldn't directly connect it to USB as the two have completely different signalling protocols. SD cards don't have the capability to be a USB slave device, so connecting it up to a USB port would likely just break something. In order to make a USB SD Card reader, you need a USB mass storage controller designed to make the bridge between the USB protocol and that used by the SD card. This could be either a chip designed specifically for the task, or a programmable microcontroller which you have written software for to allow it to act as a USB MSD and an SD card host.

If however your goal is simply to connect an SD card to a computer, the simplest solution is to just by a card reader, there are hundreds of different brands and products all largely doing the same thing. Many Laptops and PCs already have card readers.

  • I'm building a hardware sampler, see samplerbox.org (with an embedded RaspPi) for which I want to have a user SD card reader, mounted on a PCB. Now I need to connect this SD reader to the Pi, either with USB or GPIO. (I also posted here because this question may be valid for many embedded solutions, not only those based on Pi)
    – Basj
    Mar 29, 2015 at 20:41
  • If you just want to be able to plug an SD card into the Pi, why do you need to have a PCB like the one above? You can get very compact sd (and microsd) card readers which you could just mount in your enclosure - google 'tiny sd card reader' there are lots of results, e.g. adafruit.com/products/939. Mar 29, 2015 at 20:54
  • I would need the same but 1) for SD instead of microSD 2) one that I can mount on a the I/O PCB board of my hardware... I've spent countless hours to try to find such a component, and the closest I could find is the one in photo of my quesion. But if another one exist, I'd love to use it!
    – Basj
    Mar 29, 2015 at 21:05
  • If you are desperate to go down the route of having something completely custom, this thread may be of use: raspberrypi.org/forums/viewtopic.php?f=44&t=8837 There is an SPI MMC driver (SD Card) which from what I gather the person was able to make use of the use the SPI on the GPIO header to connect to an SD Card. If you refer to the later posts in that thread they were using the 3.2 kernel's hardware SPI support to achieve decent speeds. Mar 29, 2015 at 21:07

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