Fail of the Week: Blown Light Bulb Controllers

fotw-nyc-resistor-chandelier-driver

We’ve been meaning to get around to this one for many weeks now. It’s been hard to find good fail write-ups… it’s as if hackers are afraid to admit that sometimes projects fail. We hope you’ll shake off that opinion as failure is the fastest path for learning and true understanding!

[xymax] was working on a control system for a chandelier with 150 bulbs which use 5 Watts each. This project was being readied for the NYC Resistor Interactive Party which [Adam Fabio] attended last month. As deadline for the show approached, the last piece was put in place late into the night… but it was connected backwards. In a tale worthy of a slapstick movie, the reverse polarity caused a chip on all seven controller boards for this module to blow like the one seen above. But that’s not all, the laptop being used during prototyping was connected by USB and started smoking!

All of us feel the pain of this type of equipment failure. Luckily [xymax] looked for lessons to learn instead of dwelling on the mistake itself. Use protection diodes, keyed connectors, and write about your failures. Hopefully reading this will help others avoid a similar equipment-destroying mistake.


2013-09-05-Hackaday-Fail-tips-tileFail of the Week is a Hackaday column which runs every Thursday. Help keep the fun rolling by writing about your past failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.

The Worst E-Reader Ever

oled

Over on the Projects site, [Jaromir] has created a tiny device with an OLED display, three buttons, and a USB port for storing text files, be it for saving a shopping list, a cheat sheet, or the most unusable e-reader ever made.

The front of the device is simply a 96×32 pixel OLED and three buttons for ‘up’, ‘down’, and ‘open/close’. The reverse side is where the magic happens with a PIC24 microcontroller that sets up a file system on the chip, allowing [Jaromir] to write 64kB of data on what is actually a Flash drive with a pitiful capacity. Text files are viewable on the OLED, with the video below showing the front page of Wikipedia being displayed in a glorious 16×4 text mode.

It’s not a very useful device by any means, but for some reason it’s garnered a lot of skulls and followers over on Hackaday Projects. In response to that, [Jaromir] is working on version two with a new PCB and a design for a 3D printed case. Not bad for what [Jaromir] himself describes as worse than just about any phone or tablet.

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GPIB To USB, With A Python API

GPIB

If you’re not so daft as to think Arduino-based oscilloscopes and multimeters are actually useful for all but the simplest tests and measurements, you just might have some big iron sitting around your workbench from the likes of HP, or Tektronix. You might have noticed a strange port on the back of these machines, labeled GPIB or IEEE-488. This is the standard interface for these devices, and if you’ve ever priced out a USB to IEEE-488 converter, you can see why [Steven] thought it would be cheaper to build his own.

This build is an update to an earlier version we saw a few years ago. Since then, [Steven] has taken some advice from the community and replaced a bunch of resistors with proper GPIB line driver ICs, and generally cleaned up the firmware.

Because a USB to GPIB adapter is only one small part of the tools necessary to connect these old measurement devices to a modern computer, [Steven] has also been working on InstrumentKit. It’s a Python library that takes all the standardized instrument commands and wraps them up in an easy to use API. You can check out the docs for InstrumentKit here, or just look through the board files and firmware on the Github

Using A ThinkPad Keyboard Over USB

kbIt doesn’t have buckling springs, Cherry blues, or even the wonderful if forgotten Alps switches, but the keyboard found in ThinkPads has the best keyboard action of any laptop around. They would make a great USB conversion keyboard, but the board to board connector is very hard to find, and no one has yet managed to get the keyboard and track point working as a USB HID device. Until [rampadc] came along, that is.

[Rampadc]‘s keyboard adapter is built for the ThinkPad T60 keyboard, which is shared between the Lenovo T60, T61, Z60, Z61, R400, R500, T400, T500, and X41 laptops, among many others. The connector is an extremely odd proprietary deal, that can be found through the usual channels for about $5 in quantity 100. On top of this, the keyboard doesn’t have a controller – that’s offloaded to the laptop’s main board. The only electronics in this keyboard is just a matrix. Despite all this, [rampadc] managed to create a breakout board with a decade counter and an SPI GPIO expander.

The board [rampadc] made features one of the proprietary connectors, a few chips, and a receptacle for an Arduino Micro. With just a little bit of code, the old keyboard becomes one of the best portable keyboards in existence, and probably a bit cheaper than the official Lenovo USB-bound ThinkPad keyboard.

[rampadc] has a few of the expansion boards available over on Tindie should you want to build your own. It’s only cost-effective if you have one of these T60 keyboards sitting around in a junk pile; not a likely situation because these machines just don’t die.

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What’s Inside a USB Isolator?

Coil Die

 

In this acid powered teardown, [Lindsay] decapped a USB isolator to take a look at how the isolation worked. The decapped part is an Analog Devices ADUM4160. Analog Devices explains that the device uses their iCoupler technology, which consists of on chip transformers.

[Lindsay] followed [Ben Krasnow]‘s video tutorial on how to decap chips, but replaced the nitric acid with concentrated sulphuric acid, which is a bit easier to obtain. The process involves heating the chip while applying an acid. Over time, the packaging material is dissolved leaving just the silicon. Sure enough, one of the three dies consisted of five coils that make up the isolation transformers. Each transformer has 15 windings, and the traces are only 4μm thick.

After the break, you can watch a time lapse video of the chip being eaten by hot acid. For further reading, Analog Devices has a paper on how iCoupler works [PDF warning].

[Thanks to Chris for the tip!]

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Tearing Down a Cheap External USB Battery

[cpldcpu] recently received an external USB battery as a promotional gift and thought it would be a good idea to tear it down to see its insides. At first glance, he could see that the device included a USB micro-b socket used as a 5V input (for charging), a USB-A socket for 5V output, a blue LED to indicate active power out and a red one to indicate charging.

Opening the case revealed that most space was taken up by a 2600mAH ICR18650 Li-Ion battery, connected to a tiny PCB. A close inspection and a little googling allowed [cpldcpu] to identify the main components of the latter: a battery mangement IC, a 2A boost converter, a 3A Schottky diode, a few 2A N-Mosfets, a 300mA 2.5V LDO and an unknown 6-pin IC. It is very interesting to learn that every last one of these components seems to be sourced from China, which may explain why this USB battery is given for free. Do you think they designed it in-house and outsourced the manufacturing, or is this a product Digi-Key simply bought and put their name on?

Editorial Note: Digi-Key is an advertiser on Hackaday but this post is not part of that sponsorship. Hackaday does not post sponsored content.

[Read more...]

Bitbanging USB On Low Power ARMs

M0

With the Adafruit Trinket, the Digispark, and some very clever work with the smallest microcontroller Atmel offers, it looks like the ‘in’ thing to do for embedded software developers is to bitbang the USB protocol on hardware that shouldn’t support it. There are a lot of very small ARM chips out there without USB support, so it was only a matter of time before someone was able to bitbang USB on the ARM Cortex M0+.

The board above is based on an Energy Micro EFM32ZG, a very small 24-pin QFN device with up to 32 kB of Flash and 17 GPIOs. As with all the bitbanged USB hacks, the differential data lines are attached directly to the microcontroller. A 24 MHz crystal is needed, but the team behind the project is working on using the internal RC oscillator instead.

The code is portable with minimal changes between other manufacturer’s Cortex M0+ chips, and with a little work, this could become a very, very cheap USB-programmable ARM dev board, something the community could certainly use.

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