SD/MMC Fits in Floppy Edge-connector




You can attach an SD camera memory card to any homebrew DIY project that has a few I/O pins,
using ordinary connectors you probably have right now.

For more details, how to obtain free mmc device drivers, and installing various open source Linux distros on WRT54G wireless routers (and other routers and devices), go here:

This is the finished "SD floppy" connector, which has been running flawlessly inside a friend's wireless router for 6 months now:

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Step 1: 01_floppy_cable.jpg

Here is the standard PC floppy cable we will use for this hardware hack, with an SD card for a size comparison.

Step 2: 02_5.25in_floppy_connector.jpg

Here is a closeup of the 5.25 1.2 MB floppy edge connector. You can see the pin numbers (we use the even pins) in this photo.

Step 3: 03_good_pin_alignment.jpg

I tried a lot of different connectors I had laying around to find one that could be used as an SD card socket. Here a floppy edge connector is being tested for SD card fit and alignment. You can see how well the (partially inserted) SD card pins align in the floppy connector. You can see the upper connector pins reflecting from the SD card pin pads.

Also, you can see that the ridge on the edge of the SD card slides firmly into the groove in the connector plastic pin separator, which aids card alignment (when the card is inserted using the connector even pins).

It causes no harm to insert the SD card backward, because the odd pins are not used in this application.

Step 4: 04_fully_inserted.jpg

Here is a front view of the SD card, fully inserted into the floppy edge-connector. Be sure to firmly insert the card until it is all the way in.

Step 5: 05_new_sd_cable.jpg

Here is a photo of the ribbon cable already soldered into the wireless router, with the wires spread and pressed partially into the backs of the connector pins.

For more details on where to connect the wires inside your wireless router, detailed links are provided at the bottom of this page:

A closeup of the connector at this point can be seen in the next photo.

Step 6: 06_wire_even_pins.jpg

Here is a closeup of a piece ribbon cable I "peeled off" from a scrapped 25-pin serial cable. You can use part of the floppy cable if you wish.

You can see that I have carefully removed the back of the connector (by lifting the spring-loaded side clips with a small screwdriver), and pulled off the old ribbon cable.

If you accidentally bend any of the connector pins, straighten them with a small needle-nose pliers before continuing.

Spread the wires back enough to fit the connector, then push them down between the odd-numbered pins, and push them into the even numbered pins (as shown in the photo) using a small screwdriver. When inserting the wires, note that the pins on the small side of the plastic connector edge guide separator are not used in this application. You do not need to push the wires all the way in, because that will be done when the connector back is squeezed on later.

Step 7: 07_squeeze_together.jpg

Now we snap the connector back onto the connector. Then we squeeze the connector on firmly with a vise, C-clamp, vise-grips(TM), or whatever. I have even carfully used a hammer to gently tap the connector backs in place, but I much prefer a tool that applies firm even pressure, as I did for this photo.

Step 8: 08_label_and_guide_shim.jpg

Here is the completed SD floppy connector, with label attached showing which way to insert the SD card, and with a guide shim (cut from a plastic soda pop bottle) folded over and inserted to help guide the SD card into the proper pins.

It works!

For more details, how to obtain free mmc device drivers, and installing various open source Linux distros on WRT54G wireless routers (and other routers and devices), go here:

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    32 Discussions


    6 years ago on Introduction

    I had guessed that it would fit, but I didn't assume that it would actually make a connection.


    Reply 6 years ago on Introduction

    An Arduino Due might come in handy here. It runs at 3V3 and has hardware USB. However, I don't know exactly how, but it could be done. Maybe I should start trying once I receive my Arduino Due.


    11 years ago on Introduction

    hi was a floppy drive cable right?.........aaaaaaa.........what about if i use a cd drive cable............hhhhhhhhhhhhhhhhhh

    3 replies

    Reply 11 years ago on Introduction

    wont work cd drives use holes as in the left pic floppy connectors(5.25" size)use the suitable connection (right picture)and 3.14 drives use the center connector(admire the smaller number of pins)i cant put up pics now


    9 years ago on Introduction

    isnt there a floppy disc that has the sd memory device inside it
    can you read and write data
    what kind of read write speeds are available please?
    does it need a driver?
    can you modify zx microdrive cartridge for sd/compact flash also
    is it possible to use the motor to power the device/charge any battery required?
    what transfer speeds possible from 8 devices?


    11 years ago on Introduction

    hi nice trick but what does it realy for ....Ooo i understand........well what about if we attach a usb cable on the end of that cord.........well what's your opinion...................byyyyyeeeeee

    2 replies

    Reply 11 years ago on Introduction

    well uhm. This is primarily designed for the hack of the Linksys router WRT54G, which allows you to attach an SD card, and have the router interface with it. Then you can run the router with that extra memory. (You could host email server, web server, etc off your router). No usb support. Want a USB connection? you would have to buy one.


    10 years ago on Introduction

    Here's the idea I've got- need to find out if it would work. Use the SD card as the boot drive for Linux, and add it in place of my floppy drive on a desktop: a fast boot, low access time for the OS, less moving parts & less space...


    12 years ago on Introduction

    i was wondering if this could be used with an old laptop, i'm buying a compaq lte5300{manufactured 1997}, and it has no usb or cd-rom. i would like to know if it is possible to replace the laptop's floppy drive with a SD card? maybe then i could use the SD as its removable storage, would be nice to use a 2gb card, sure beats any floppy disk!