It’s well-known that buying Flash storage devices from cheap online retailers is fraught with danger. Stories abound of multi-gigabyte drives that turn out to be multi-megabyte ones engineered to falsely report their capacity. So when [Jason Gin] found a source of 64GB Toshiba eMMC chips for only $6 per device he bought a few, but was prepared for disappointment.
To test them, he decided to use an SD card interface. There are minor differences between eMMC and SD, but the interfaces are electrically the same and in most cases an SD controller will happily do business with an eMMC. It was not however an easy task to connect the two — these eMMCs were in BGA packages, hardly the easiest ones to work with. He resorted to dead-bug soldering the relevant interface wires to SD lines, and connecting up his computer.
His first attempt was something of a failure, wiring the chip to the PCB of a cheap USB-to-SD adaptor. This did not put him off though, he followed it up by cracking open a very old 2GB SD card that contained a PCB instead of being potted, and soldering his eMMC in place of its Flash and controller. This even fit in the original SD housing, and met with success when plugged into more reliable SD card readers. He was thus able to confirm the capacity of his chips.
His blog post is worth a read for more than just the very fine soldering involved. He takes us through some of the intricacies of SD interfacing, as well as talking at length about the decoupling and termination required to make a reliable connection. We particularly like his use of an area of unconnected BGA balls as prototyping space for decouplers.
If you marvel at the exceptional dexterity required for hand BGA work, we’ve a couple of other treats for you. There is this TI infra-red sensor BGA soldered to a piece of stripboard, and this wafer-level chip package soldered to an SOIC prototyping board.
An SD card is surely not an enterprise grade storage solution, but single board computers also aren’t just toys anymore. You find them in applications far beyond the educational purpose they have emerged from, and the line between non-critical and critical applications keeps getting blurred.
Laundry notification hacks and arcade machines fail without causing harm. But how about electronic access control, or an automatic pet feeder? Would you rely on the data integrity of a plain micro SD card stuffed into a single board computer to keep your pet fed when you’re on vacation and you back in afterward? After all, SD card corruption is a well-discussed topic in the Raspberry Pi community. What can we do to keep our favorite single board computers from failing at random, and is there a better solution to the problem of storage than a stack of SD cards?
Continue reading “Single Board Revolution: Preventing Flash Memory Corruption”
[jamesone111] bought a Transcend WifiSD card, presumably for photography, but it may just have been because he heard that they’re actually tiny Linux servers.
He read a post about these cards on the OpenWRT forums. They’re all a similar configuration of a relatively large amount of memory (compared to the usual embedded computer), a WiFi chip, and an ARM processor running a tiny Linux install. The card acts as a WiFi access point with a little server running on it, and waits for the user to connect to it via a website. It also has a mode where it will connect to up to three access points specified by the user, but it doesn’t actually have a way to tell the user what its IP address is; which is kind of funny.
[jamesone111] hacked around with the Transcend card for a bit. He found it pretty insecure, which as long as you’re not a naked celebrity, shouldn’t be a huge issue. For the hacker this is great as it opens up the chance of hacking the firmware for other uses.
Some have already pulled off some cool hacks with these cards. For example, [peterburk] hacked a similar card by PQI to turn his iPod into a portable file server.
[gilmour509] posted a thorough gallery of a new custom-built computer and case made to look like a 1995 IBM Aptiva. While the whole build is impressive, the most clever part involves a 3 1/2″ floppy disk that hides an SD card and works like a regular USB flash drive when inserted into the floppy drive.
He makes use of the fact that floppy disk edge card connectors have the same spacing as SD cards. Add in a hacked USB card reader, some careful cutting and assembly, and [gilmour509] has a very convincing floppy drive with gigabytes of space.
The best part is that with everything put together, the floppy disks and floppy drive look completely unmodified. He even made the file explorer icon show a floppy drive.
The faux-Aptiva gallery includes the full build, but skip to about 2/3 down to see the floppy SD card section.
Continue reading “Floppy Drive Hides SD Card Reader”
About a year ago, Intel announced they’d be launching a new platform stuffed into an SD card. Imagine – an entire computer packaged into an SD card, with nine whole pins for power and I/O. Cooler heads prevailed, the Intel Edison was launched, but the idea stuck; why can’t you fit an Arduino in an SD card?
[kodera2t] found out there’s no real reason why you can’t put a small microcontroller inside an SD card. For his Hackaday Prize entry, he created the SDuino, and it’s exactly what it says on the tin: an ATMega328p stuffed into a microSD adapter.
Unlike the other microcontroller stuffed in an SD card platform — the Electric Imp, [kodera] is, for the most part, respecting the standard pinout for SD cards. The MISO and MOSI signals are reversed, of course, one of the grounds on the SD pinout is tied to an analog input pin on the microcontroller, and the chip select on the SD pinout is ignored completely. Other than that, it’s the closest you’re going to get to an SD card with a microcontroller.
Let’s say you use an SD card-base portable audio recorder for work – doing an interview, perhaps. Things go well until one day, you turn the recorder off before stopping the recording. Without pressing that big red Stop button, the file doesn’t close, and you’re left with a very large 0kB file on the SD card. How do you get it back? There are tools that will do it for you, but they cost money. You can do it yourself with a hex editor, though, and it’s actually pretty easy.
The software required for this feat of data recovery is Roadkil’s Disk Imager to dump all the bits on the SD card to an image file, the free version of ISO Buster to show the block addresses and length of each file, and the hex editor of your choice. The process starts as simply an experiment for hot to create an MP3 file by cutting and pasting bits into a hex editor. A good file was found in the hex editor, copied to a new file, and played. Everything works so far; great.
For the actual data recovery, a spreadsheet was created to make an educated guess as to where the lost file should be. Starting at this address, about 90MB of data was copied into a new hex editor window. This is where the recovery hit a snag. Because the SD card was plugged into a Mac before, a bunch of data was written on the card. This went into the first available place on the disk, which just happened to be the header of the lost MP3 file.
That’s not a problem; there’s already the header from an MP3 file sitting in a hex editor from the first experiment to see if this was possible. By copying a few hundred bytes to the front of the lost file, the file was corrected just enough that an MP3 player could reconstruct the file.
It’s not perfect – the first fifty seconds of the interview was garbled. The rest of the interview was saved, though, and that’s much better than losing the entire thing. Thanks [Lewin] for sending this one in.
Continue reading “Manual Data Recovery With A Hex Editor”
The idea of a pirate box is pretty simple. All you need is a tiny Linux system with a WiFi adapter, a bit of storage space, and the software that will allow anyone to upload a few files to the server and an interface that will let anyone on the network download those files. In practice, though, a pirate box is a mess of wires and power adapters – not the pocketable device a WiFi file sharing box should be.
[Chris] came up with a much smaller file sharing beacon. It’s not based on a router; instead, [Chris]’ build uses an ez Share WiFi microSD adapter. It’s a device meant to push pics taken by a digital camera up to the Internet, but by configuring the software just so, up to five users can connect to the adapter and pull files down from a microSD card. The build only requires putting power to the correct pins. A LiPo battery and charge controller takes care of this problem.
There are a few shortcomings to this project – [Chris] doesn’t know how to upload files to the device. Maybe someone sufficiently clever can figure out how to make that work. Still, if you’re ever in a situation where you’d like to share some files with people in the same building, this is the device you need.
Thanks [Jake] for the tip.