SD cards are great inexpensive storage for your embedded project. Using SPI, they only take a few wires to hook up, and every micro-controller has a FAT file system interface to drop in your project. Problem with SD cards are the connectors.
Usually connectors cost more than the brains of your project, and the friction fit, spring loaded contacts are not ideal for temperature swings, humidity and high vibration applications. Wouldn’t it be nice if you could just solder the thing down, especially if you know you are never going to remove it?
[Timothée] decided to try and succeeded in reflow soldering a Micro SD card direct to a breakout board. While starting as a what if experiment, the PCB was laid out in Ki-Cad and sent off to a fab. Once returned the Micro SD was fluxed, tinned and fluxed again, then reflowed using an IR setup.
The end result is a handy breakout board where you never have to worry about someone swiping the card to jam in their camera, and is ready for any breadboard project.
For nearly every problem, it’s possible to engineer a solution, even if you’re dealing with an extraordinarily niche problem that might only apply to yourself. [Joel] wanted to be able to program the microSD card in his BeagleBone with a new bootloader or file system without removing the SD card from the target board. This is a peculiar requirement, and it’s highly doubtful a product or even a circuit exists for such a function. This meant [Joel] would need to roll his own board to accomplish the task.
The board is remarkably simple, housing a single microSD socket, two expansion headers for a microSD sniffer for a computer and an embedded board, an FTDI header, and a pair of 4-bit multiplexer/demultiplexers. The operation of the device is fairly straightforward: send a signal down the FTDI cable, and the board switches the onboard SD card from one device to another.
[Joel] has a video of his screen that shows him pulling off in-circuit SD card reading and writing. You can check that out below.
Continue reading “The In-Circuit SD Card Switch”
In case you weren’t aware, that little ‘write protect’ switch on your SD cards probably doesn’t do anything. It’s only a switch, really, and if an SD card reader doesn’t bother to send that signal to your computer, it’s completely ineffective. Then there’s the question of your OS actually doing something with that write protect signal.
The better way to go about write protecting an SD card is using the TMP_WRITE_PROTECT bit on the SD card’s controller. [Nephiel] came up with an amazingly small device to set that bit, with the entire circuit fitting inside an old Playstation memory card.
[Nephiel] based his project on [Karl Lunt]’s SD Card Locker we saw late last year. [Karl]’s SD Locker uses an ATMega328 microcontroller, a pair of AA batteries, and an SD card socket to perform the bit toggling. This is still a very small device that fits inside an Altoids tin, but [Nephiel] thought he could make it smaller.
The new and improved version uses an ATTiny85 for SPI access to the SD card. A single button and LED serves as the user interface: with the LED off, the SD card is writable. Press the button, the card is locked, and the LED lights up.
[CNLohr] spends most of his time on the Internet, but sometimes real life drags him away from his keyboard. These “vacations”, as he calls them, don’t have a good Internet connection and forces him to rely on flaky cell phone connections that go up and down at the drop of a hat. Figuring this would be a great opportunity for some hardware hacking, [CNLohr] came up with an ‘Internet-o-mometer’ – a device powered by a Trancend WiFi SD card that uses an 8×8 LED display to show the current status of his phone’s Internet connection.
This build uses the Trancend WiFi SD card motherboard we’ve seen before. When the card boots, it tries to connect to his phone’s WiFi connection. When it connects, a green smiley face is displayed on the LED matrix. When a whole lot of files are downloaded or, more specifically, the ping to google.com is more than 4 seconds, a red frowny face indicates the Internet connection is down.
In other Trancend WiFi SD card news, a whole lot of people including [Dan Krause] (thanks for the tip) have been working on a complete replacement OS for these neat little cards. Right now the OS is in very rough shape, but there is a pre-built system available should anyone want to experiment. [CNLohr] is also working on a compact, double-sided version of his SD card motherboard and we’ll be happy to feature a link to his Tindie store when he sends that in.
A few days ago, one of [Severin]’s SD cards died on him, Instead of trashing the card, he decided to investigate what was actually wrong with the card and ended up recovering most of the data using an Arduino and an immense amount of cleverness.
SD cards can be accessed with two modes. The first is the SDIO mode, which is what cameras, laptops, and other card readers use. The second mode is SPI mode. SPI is slower, but much, much simpler. It turned out the SDIO mode on [Severin]’s card was broken, but accessing it with an Arduino and SPI mode worked. There was finally hope to get files off this damaged card.
[Severin] used a few sketches to dump the data on the SD card to his computer. The first looked at the file system and grabbed a list of files contained on the card. The second iterated over the file system and output all the files in hex over the serial port. With a bit of Python, [Severin] was able to reconstruct a few files that were previously lost forever.
Even though the SD card was completely inaccessible with a normal card reader, [Severin] was able to get a few files off the card. All the sketches and Python scripts are available on the Githubs, ready to recover files from your broken SD cards.
[The Backwoods Engineer] tested out a new accessory kit for the STM32-F4 Discovery board. The image above shows two boards communicating with the UDP protocol. Notice the extra PCB into which each Discovery board has been plugged. This is a third-party add-on which adds Ethernet, RS-232, SD card slot, and a connector for LCD or Camera. We’ve had one of these F4 Discovery boards on hand for a while and haven’t figured out a good way to connect external hardware to the huge dual pin-headers. This doesn’t solve the problem — the base board also includes dual headers to break-out all the pins — but having Ethernet, serial, and SD certainly reduces the need to add all that much more. The other drawback to the hardware is that the sample firmware is targeted at the IAR Embedded Workbench which is neither free, nor in the realm of affordable for hobbyists.
The NIC used on the baseboard has auto-crossover capabilities so the boards were connected using a regular Cat6 patch cable. This example has the boards constantly sending UDP packets with the module on the right reporting status information to a terminal via the serial connection.
Here’s an inexpensive Arduino-based MP3 Jukebox (translated) which [Jose Daniel Herrera] put together.
He spent some time making sure that it looked great sitting on a shelf with his other audio equipment. This started with a wooden box which is some reused packaging. We’re not familiar with the ‘iNFUSiONES’ product; perhaps it’s tea or tobacco? At any rate, to this he added a custom face plate to host the character LCD, rotary encoder, two buttons, and to act as a grill for the two speakers.
The speakers and their accompanying amplifier circuitry were pulled from a portable speaker set. He combined them with a VS1002d MP3 decoder module, SD card breakout board, and the Arduino itself. In addition to the overview post linked above, there is also a collection of assembly photos, and a post discussing the way he arranged the code for the control systems (translated). See and hear the unit in action in the clip after the break.
Continue reading “Arduino MP3 Jukebox”