Share this project


Share this project

Mini MicroSD Reader for Android Smartphones & Tablets's video poster

An external card reader that enables you to use MicroSD card on your Nexus/Android tablets and Android smartphones. Read more

San Mateo, CA Hardware
Share this project
pledged of $5,000 goal
seconds to go


This project was successfully funded on May 5, 2013.

An external card reader that enables you to use MicroSD card on your Nexus/Android tablets and Android smartphones.

San Mateo, CA Hardware
Share this project

About this project

Hello world! You like your Nexus tablet but you hate the fact that it doesn't have a built-in SD card reader for storage expansion? My brother and I felt that way when we first got one in July 2012. So we decided to do something about it -- make one for it. After many months of hard work, finally we have something that we feel good about and we want to share with the world.

What does it do?

Well, it is just like a SD card reader that you use on your computer, except it is for Android tablets and smartphones that have MicroUSB port. You can use it to read/write MicroSD cards, copy files between your phone/tablet and a MicroSD card.

It supports MicroSDHC cards up to 32GB (max capacity by SDHC standard), and MicroSDXC cards up to 64GB (max capacity available on the market). SDXC standard supports cards up to 2TB -- this reader should support future MicroSDXC cards of higher capacity up to that, but we have no way of testing it right now.

Will it work on my device?

It works with the newly released HTC One and Samsung Galaxy S4.

It took a lot of time, but we were able to find one USB IC chip that supports all different types of mobile devices and chipsets that we could get our hands on. So far, we verified that it works with the following devices:

  • Samsung Galaxy S2, S3, S4, Note, Note 2, Galaxy Express, Galaxy Note 8.0 tablet; Class 1 support.
  • Motorola RAZR M, RAZR HD, RAZR MAXX HD, Xyboard 8.2" Tablet; Class 1 support.
  • HTC One, HTC First, HTC One X+, Evo 4G LTE (Sprint), DROID DNA; Class 1 support.
  • Samsung Galaxy Nexus, Google Nexus 7 & Nexus 10; Class 2 support.
  • Nook Color, Kindle Fire (non-HD); Class 3 support.
  • Tablets using RockChip & AllWinner chips; Sonicview N710; Class 1 support.

Note: "Class" 1/2/3 is used to classify how well the reader is supported on the particular mobile device. It is not related to the "Class" of the SD card. It supports SD cards up to Class 10.

Class 1: it is supported by the phone/tablet out of box, no rooting or other privileged software needed. Class 2: supported using 3rd party software such Media Importer from Play Store, with some limitations; root device and install 3rd party software such as StickMount or USB OTG Helper to remove such limitations. Class 3: a custom ROM such as CyanogenMod is needed.

It should work with most other devices that support USB host or USB-OTG (On-The-Go) as long as the device maker doesn't intentionally disable such functionality. For the technically inclined, it has been tested and verified on all four major mobile SoCs(system-on-a-chip): Qualcomm Snapdragon, Samsung Exynos 3, 4 & 5, Nvidia Tegra 2 & 3, TI OMAP; as well as on RockChip and AllWinner chips. It is expected to work on future version of those SoCs -- but this is not guaranteed, see Risk section.

Warning to owners of devices listed as "Class 2" and "Class 3" supported: rooting your device or flashing a custom ROM most likely will void product warranty and may cause irreparable damages to it. We don't encourage you to do that just to use this reader and can't be held responsible if you choose to do so, especially if you don't know what is "rooting" or "custom ROM". Only consider to support for this project if you already done rooting or flashing custom ROM or clearly know what you are doing and plan to do so anyway. Support on "Class 3" device can NOT be guaranteed since different custom ROM may behave differently and even products from different batches can have minor difference affecting how it will work; this especially true for Amazon Kindle Fire, for which the USB support is fragile and inconsistent at best.

The design

We spent a lot of time working on the usability of the reader and tweaking the form factor. We think our MicroSD card reader is better designed than any other SD card reader product that's available on the market.

Coin-size, take it anywhere you go

It has a small hole so you can attach it to a small clip hook or snap hook (one will be included with every reader), which can then be attached to your key ring or a snap hook inside your backpack, laptop bag or messenger bag.

Never lose the cap

You often lose the caps that come with memory card readers and USB thumb drives? Not this one. When the reader is in use, the cap itself can be attached to the snap hook. When the cap on, it will stay on -- there are 2 locking mechanisms to keep it stay on.

Use it with the case on (phone or tablet)

Many people use a protective case on their phones/tablets. This reader has been designed in such a way that it can be used with a case up to 2mm thick.

How we got here

Andy first talked to Rich about the idea back in July 2012. Over the weekend, Rich put together a quick proof of concept. After many months of hard work, finally we finished CAD design, selection of USB IC chip and PCB design, and conducted extensive testing.

Note: prototype here is shown in "raw" plastic material. The finished product will have a layer of coating to make it look much nicer. Tentatively we are planning for a glossy Piano Black finish; if there are enough supporters, we will consider more color choices.

What's next

It is expensive to make the tools necessary and buy the components in volume to make this into a real product. That's why we need your help! If this project is successfully funded, this how the money will be spent and the schedule:

  • Design & making of the steel mold needed to make the plastic casing, 3-4 weeks
  • Purchasing IC chips and other components/material, 1 week (in parallel with mold making)
  • Making of PCB, 1 week and more depending on volume (in parallel with mold making)
  • Pilot run, testing and verification, 1 week
  • Production run, QA & packaging, time frame depends on volume
  • Express bulk shipping to US and shipping to kickstarter supporters!

Rich has talked to several manufacturers and selected one as a manufacturing partner candidate. They have been great helping us understand the manufacturing process and are very open minded about working with a tiny fish like us. With your support, we believe we can make it happen.

Risks and challenges

Unlike USB on PC, USB support on mobile devices is under each individual device manufacturer's control. It is possible that a device maker may choose to disable USB support in their future devices (possible) or disable USB support in future software update of existing devices (possible though unlikely). Thus it is possible that this card reader works on your device today, but may not work in the future or in future devices.

When the manufacturer has big orders, there could be some delay in getting us in their production run schedule. We will try to get our production into their schedule as early as possible.

Quality control is always a challenge for electronic products, even for something as small and simple as a SD card reader. We have talked to the manufacturer extensively about their QA process and even ask them to add additional testing steps -- and they agreed to it. We will use high quality components and materials to make sure it will be a quality product. E.g., the IC chip that we selected is one of the most expensive ones on the market and is what being used in name brand SD card reader products.

Learn about accountability on Kickstarter


  • No. Currently USB-OTG is not supported on Nexus 4. Seems there is some hardware issue preventing that, and most likely software alone can't fix it.

    Last updated:
  • No. HP Touchpad's USB port doesn't provide power to connected devices. This device (and any other Mass Storage device) needs some power to work, so it won't work with HP Touchpad, no matter what software is installed there -- it's a hardware limitation.

    Last updated:
  • (1) "Out-of-the-box" with stock system software without any modification, using Media Importer App from Play Store, you can view/play files/video etc. stored on a MicroSD card (copied via a PC), but you can't write files to the card (when connected to Nexus). You have to use a PC to write files to the card.

    See FAQ of the app:

    (2) Root the system, install Stick Mount or USB OTG Helper from Play Store, you can read/write MicroSD card using this reader, copy files between device's internal storage and the card -- like what you normally do on a PC.

    Last updated:
  • This reader works with HTC One out of the box.

    Last updated:


  • You selected
    Pledge $1 or more

    43 backers

    "Thanks for all the fish" reward: a heart-felt Thank You for supporting us! One card reader (world-wide shipping included) to the first three who leave a comment to give a correct "Answer to the Ultimate Question of Life, the Universe, and Everything" -- the first three supporters ONLY.

    Estimated delivery:
    Ships anywhere in the world
  • You selected
    Pledge $8 or more

    100 backers All gone!

    Early bird special! One card reader, standard world-wide shipping included.

    Estimated delivery:
    Ships anywhere in the world
  • You selected
    Pledge $12 or more

    5,600 backers

    One card reader, standard world-wide shipping included.

    Estimated delivery:
    Ships anywhere in the world
  • You selected
    Pledge $2,048 or more

    0 backers Limited (2 left of 2)

    Be an insider! One card reader and one of hand-made prototypes, world-wide express shipping included. Plus a lunch with Andy at Mountain View, CA to discuss how the project has been developed. Travel, lodging and any other expenses are not included except for the lunch. Plus a guided tour of the factory in ShenZhen, China where the card readers will be made, accompanied by Rich. To see this very product being made at the factory, you must be able to travel according to the production schedule. A one-week advance notice will be given. Otherwise you can travel to tour the factory at your convenience in June/July 2013; a one-week courteous advance notice from you is expected in this case. Travel, lodging and any other expenses are not included, except for local transportation and meals on the day of the tour. You can have up to 3 members in your group (yourself included) for the tour.

    Estimated delivery:
    Ships anywhere in the world

Funding period

- (30 days)