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Making a W SD Card Image

trent edited this page May 3, 2019 · 1 revision


In a few rare cases it can be helpful to re-image your SD card for W/. As the cards age they may need to be replaced (think guitar strings, saxophone reeds, or drum sticks), so you can regain Izzy like so.

The SD Card?

Yes! W/ stores the 8hours of 'tape' onto a micro SD card hidden inside the module. You can access it by removing W/ from your modular case. Look at the rear edge of the module where the power & i2c connectors are and you should see the black & red/purple edge of the SD card, immediately next to the 6pin i2c connector, sandwiched between the two circuit boards. Most modules use a 'push' action card holder, so you can gently push the card into the module, and then release and it should spring back toward you. If this doesn't work you can also just grab the card and pull it toward you with a fingernail. Or use a pair of needle nose pliers very carefully.

The particular card has been chosen to be ideal for W/'s purposes. We use a 4GB, Class 10, micro SD card. In testing we tried a lot of different cards, and found this to be the most reliable & fastest for our application. If you're going to replace the card yourself, we recommend a Class 10 card, and either 4GB or 8GB (note 8GB will not extend your tape time currently). 4GB cards tend to have faster access times. In particular we discourage using the more modern 'Ultra' or 'Extreme' speed cards- They sound like they'd be great, but W/ uses the SD card in a very non-traditonal way meaning these cards actually perform far worse than the older ones, and you'll likely have audio dropouts in your recorded files.


W/ does not have an 'operating system' or a 'file system', so in reality you can just drop a new card in and it should 'just work'. However! We image all of the factory cards with a FAT32 file-system and a 'file' called tape.bin. The reality is this isn't a real file, but just a hack that allows your computer to copy the raw data from the card for some as yet imagined functionality. This image is primarily used to get Izzy onto the module.

If you've already done the tutorial and just want to safely image a card, you can simply open your OS's disk utility application and format the card with a FAT32 filesystem. No need to copy the tape.bin file or any other gymnastics. If you want the official image, head below for the detailed / dangerous instructions.


Mac OS


Official Image

The way we create SD card images in-house is using the infamous dd command-line utility. This program allows you to directly copy data from one disk / partition to another. IT ALSO ALLOWS YOU TO OVERWRITE YOUR OPERATING SYSTEM WITHOUT WARNING. Seriously. Please be careful & follow the instructions if you're going down this route. If you're unsure of the correct command, ask a friend, ask on a forum, look on stack overflow. We take no responsibility for mistakes here.

Ok! Disclaimers aside, the process is actually very simple once you know what you're doing! There's a few steps:

  1. Find the address of the SD card
  2. Unmount the filesystem (for already formatted cards)
  3. Copy the image to the card
  4. Unmount the card

Note these are slightly different on Mac & Linux (Windows unknown), but it should work in general

Find the card address (Linux only?)

  1. Make sure the card is removed (or remove it from the computer if you already put it in).
  2. Open a terminal window
  3. Type ls /dev/sd*
  4. Insert the card
  5. Type ls /dev/sd* again!

You should see a new entry or two in the output. Write down the name that newly appeared. On my system I saw: /dev/sda /dev/sda1 /dev/sda2 /dev/sda3 and then after: /dev/sda /dev/sda1 /dev/sda2 /dev/sda3 /dev/sdb /dev/sdb1 In my case I note down the /dev/sdb and /dev/sdb1 entries. Usually a newly added device will have a higher letter (eg b is higher than a).

Note that you will likely have /dev/sdN and /dev/sdN1 (where N is a lowercase letter). The version without the number represents the card itself - this is where you will flash the image. The version with the number is the 'partition' which may contain data, and will need to be 'unmounted' before we can proceed.

Please be careful here! /dev/sda in the example above is my computer's hard disk! You don't want to copy the W/ image there!!!

Unmount the filesystem

On Mac OS, when you insert the card it will automatically mount any file system it finds. Before we can copy the image the file system needs to be unmounted (nb: this is different from 'ejecting' the card!).

In Terminal type: FIXME: i believe the below command is actually for linux umount /dev/sdN1 where the N is the letter from the previous step.

In my case this was /dev/sdb1, but it could be sdc1 or some other letter for you. It almost certainly won't be sda1.

Copy the image

Now the card is ready to be have the image applied.

  1. Download the image by following the link and clicking the download button in the top right.
  2. In Terminal, navigate to wherever you downloaded the file. This will likely do it cd ~/Downloads/.
  3. Type ls *.iso and you should see Wimage.iso. If not, you're in the wrong folder!

Now it's time to burn it! This is the command that can erase your hard disk, so make sure you get it right!

You will need to change the of=/dev/sdN part of the following command. Replace the sdN with the card name you noted in the first step. In my case it was sdb, but yours could be different. Again it will not be sda.

So now that you've figured out your of (output file), put it into the following command:

sudo dd if=Wimage.iso of=/dev/sdN count=83055

This will take ~1 minute. There will not be any status update. It might look like nothing's happening, but just count to 60, and you should see a success message. You now have an official W/ tape image!

Unmount the card

On Mac OS, the new image will automatically mount after copying, so we need to eject it before removing. You can just eject it from the desktop, or practice your Terminal chops by repeating step 2 above:

umount /dev/sdN1 where the N is the letter from the first step.

Remove the SD card from the computer. Gently re-insert the SD card into your module- the side with text faces the dinosaur landscape. Reinstall the module to your case & power up! You should see the yellow mode light at top turn on. If instead you see the yellow record light blinking, it means W/ can't find your SD card. Make sure you've correctly inserted the card, and that it hasn't fallen out into your case. If you continue to have problems, please send us an email and we'll do our best to help!

Backing up an SD Card

While there's not much you can do with it at present, perhaps you want to catalogue your recorded sounds for later recall? Or maybe you have an old card you want to replace? In this case, you can make an image of your existing SD card, rather than using the blank Wimage.iso above.

It's another simple dd command, but with that comes all the same warnings & risks mentioned above. The process is relatively simple:

  1. Insert the card to the computer
  2. Unmount the Filesystem (Mac OS only)
  3. Create an image of the card onto your computer.

Step 2 can be seen above, so the magic command for step 3 is: sudo dd if=/dev/sdN of=~/myImage.iso

  • You'll need to change if=/dev/sdN to use your SD card identifier (mine was sdb).
  • You can change the directory / filename in of=~/myImage.iso this will create an image called myImage.iso in your home directory
  • Nb: this will copy the entire 4GB of the card, regardless of how much audio is recorded on your tape. For now it's the best we've got, but make sure you have enough HDD space before continuing.

We're considering making some better tools for this kind of backup & card preparation, but if you've got ideas we'd love to see what you create too!