3 Replies Latest reply on May 20, 2015 6:51 PM by CMata_Intel

    Connecting SD card interface to mini breakout board

    Buis

      I wish to use the SD interface on the mini breakout board. I bought a card holder, with GND, MISO, SCK, MOSI, CS, 5V, 3.3V and another GND pins. After reading a lot of documentation about SPI and SD, I managed to deypher the pinouts on the mini breakout board to this: J20.12: MOSI, J20.13: MISO, J20.2: 3.3V, J20.11:SCK, J19.3: GND, J19.14: CS.

      Hooking it all up was quite a task; since the pinouts are really close to eachother, there is no way to do it "nicely" on a breadboard. I connected the J20 row to the breadboard and made some plugs for the J19 row. Connected it all and inserted FAT formatted 1G SD card. Then boot.


      Now I wished to see if the card is recognized.

      dmesg | tail -n 10 listed nothing resembling an SD card.

      cd /media/sdcard nothing there

      ls -la /media: nothing there


      What do I do in Linux? How to check if I hooked it up correctly? Is there an easier way to work with the mini breakout board? regular breadboard wires are too thin and there is a conductive surface on the bottom of the compute module itself. Seems there must be a better way...

      I am very sorry for asking such noob questions, but is there an Edison/Yocto reference for cases such as this?


        • 1. Re: Connecting SD card interface to mini breakout board
          Bunsen

          The Edison requires a level shifter between its native 1.8V I/O and the SD card's 3.3V I/O.  Sparkfun's microSD block uses a TXB0108, Intel's Arduino board uses a TXS0206 (which isn't a convenient choice for hobbyists since it only comes in a fine-pitch BGA package), and I've got a custom board running with a MAX13035, none of which are really breadboard-compatible.  Those are all set up between the Edison's SD/MMC interface and the card, though, rather than using the Edison's SPI lines.  No manual intervention is required in linux to make the card appear as a disk, though I don't remember if it automounts anything in /media.

           

          If your card holder only breaks out the SPI pins of the SD card, you can connect those through unidirectional level shifters to the Edison's SPI interface, but I don't know if there's an easy way to make linux recognize it as a disk through the SPI interface.

          • 2. Re: Connecting SD card interface to mini breakout board
            Buis

            Thanks for the insight!

            When I first started with Edison, I thought it would be a great product to work with. Now, having to find out the really really hard way how to resize the root partition, trying to get MP3 audio to work over bluetooth, attempting to expand storage with an SD card, I feel there is a large gap between the very easy and the really really hard. How could I have ever known I would need level shifters?

            Is a USB stick easier? Or do I go with dropbox...

            Would someone please join me in building a list of things to do with Edison and how to do them? Keeping them up to date?

            - how to practically wire up external devices to the mini breakout board

            - how to expand local storage with SD, USB, whatever

            - how to automate/remember bluetooth A2DP connections and re-pair automatically

            - how to play (compressed) audio (video?) over miracast, airplay

            - ...ideas welcome

            • 3. Re: Connecting SD card interface to mini breakout board
              CMata_Intel

              Hi Buis

               

              In order to use an SD card interface with the mini-breakout board I think you could take a look at the Schematic of the Arduino Expansion Board (SD Card - Section)

               

              If you want to wire something to the mini breakout board you must always check the hardware guide of the Edison Compute Module and the Mini-Breakout board.

              More documents in: Intel® Edison Documents and Guides

               

              You can use an SD or USB drive for storage, you can also create your own image with different partitions. [Intel® Edison Boards — Board Support Package (BSP) User Guide]

              About the A2DP connections; you can check the Intel® Edison Boards — Bluetooth* User Guide

              Miracast, airplay.... Do you want to attach a webcam to the board and then stream video to another device? For example you can use gstreamer too.

               

              The Edison Module and their expansion boards are very recent so there are a lot of things that haven't been done yet. If you want to work in these things I encourage you to keep posting your doubts, questions and feedback in the communities, you will find a lot of helpful people that will guide you.

               

              I hope this gives you an idea on how to start working on those topics.

               

              Best Regards;

              CMata