Shrink Your Raspberry Pi With MicroSD Card Slot





Introduction: Shrink Your Raspberry Pi With MicroSD Card Slot

About: I am an electrical engineer. I graduated from U of Waterloo. I used to work for Adafruit Industries as an EE. Now I work for Sony PlayStation as a EE.

The Raspberry Pi itself is about the size of a credit card, but it only has a standard full sized SD card slot. When you plug in a standard full sized SD card into it, the card sticks out of the outline of the Raspberry Pi, making the overall size slightly larger.

My solution is to add a microSD card slot to the Raspberry Pi permanently, and in a location that does not stick out of the original Raspberry Pi outline.

There are two solutions that I have done. One is easy, the other requires slightly more soldering skills.

For the first easy method, you need a microSD card to full sized SD card adapter, some solid core insulated wire that is thinner than 24 gauge, and some solder plus equipment. The idea is to place the adapter underneath the Raspberry Pi, right beside the SD card slot. The pads on the adapter should be facing up, this way, each pin on the adapter will be right next to the corresponding pin on the slot. Solder small pieces of wire between the adapter and the slot's pins. You also need to short out the "card detect pins" of the original SD card slot to trick the system into thinking that a card is inserted.

Using this method, the overall thickness of the Raspberry Pi does not increase at all. The microSD card will boot Linux normally while it is plugged into the adapter you've just soldered on, and standard full sized SD cards will still work while plugged into the original full sized SD card slot.

For the second slightly harder method, a Molex brand surface mounted microSD card slot is used, part number is 502702-0891. It is placed upside down on the bottom of the Raspberry Pi board, in the flat area underneath the 3.3V regulator. It is attached securely using double sided sticky tape, which also insulates the microSD card slot from the Raspberry Pi PCB. After the new microSD card is secured in place, 30 gauge Kynar coated wire is soldered between the pins on the microSD card slot and the original full sized SD card slot. Do do this correctly, you need to double check which pin on the microSD card slot corresponds to which pin on the original full sized SD card slot, they are different by one pin. Also, you need to wire the "card detect pin" of both slots together.

Using this method works perfectly too, Linux will boot from a microSD card in the newly attached microSD card slot, and it will still boot from a full sized SD card in the original full sized SD card slot.

Note that using two cards at once is impossible because the signals are shared, and may cause damage to the cards so don't even bother trying it.

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    20 Discussions

    here is a idea, desolder the card detect pin and wire in a spdt micro switch. center pin goes the pi and each side goes to one card socket. this was you can have 2 cards plugged in at the same time. you would also need to do this to the power line as well

    1 reply

    this idea would work, you would need to reboot completely between toggling the switch, but imagine having an entire collection of different SD cards and then having something else control which one to boot from.

    Adafruit solved this problem with this elegant little adapter.


    4 replies

    As to the 'why they didn't design with a MicroSD in the first place' question, I bet price had much to do with the decisions made. Also are full size SD cards cheaper and quicker than microSD cards of the same capacity? The kids and I have been enjoying our pi for the last couple of weeks.

    6 replies

    The main reason was SD card were cheaper than micro-SD's. although they are similar in function, they knew that micro-SD'd have those adapters and knew that using an SD card instead will cover more compatibility.

    The foundation stated several reasons for the choice. The two that stood out the most is it's harder for kids to lose a full size sd card and that the connector itself is more robust and will hold up longer.

    True, but the discussion is about full-size SD card versus mirco SD.  There's no technical reason not to use micro, but as stated above, a lot of Pis are going to be used by kids and the full-size is easier to insert and harder to lose.

    I was thinking to do something simualr...

    My idea was to Shrink the MicroSD adapter... because most of the inside of the adapter is just air/plastic. so i was thinking make the MicroSD adapter the same size as the receptical. so i dont need to change anything permenant and everything still fits within the outline.

    1 reply

    I can do this, it'll be basically be a custom PCB with a microSD card slot on the back. It might make the Raspberry Pi thicker though.

    Yes, if you want to do t that way, go ahead.

    But if I have both slots, I can still use a full sized SD card when I want to.

    I have two 16 GB class 10 cards to work with right now, one is micro and the other is full sized. I like trying out different Linux distributions so swapping cards is useful.

    When I first saw the RaspberryPi I wondered why they didn't design with a MicroSD in the first place, and whether a micro socket could be retro-fitted  Looks like you've answered the second part of the question.
    Now all I need is a RasPi.  Placed my order a couple of weeks ago . . .

    1 reply