What do fitness trackers have to do with bacterial cultures in the lab? Absolutely nothing, unless and until someone turns a fitness band into a general-purpose optical densitometer for the lab.
This is one of those stories that shows that you never know from where inspiration is going to come. [Chinna Devarapu] learned that as a result of playing around with cheap fitness bands, specifically an ID107HR. A community has built up around hacking these bands; we featured a similar band that was turned into an EEG. With some help, [Chinna] was able to reflash the microcontroller and program it in the Arduino IDE, and began looking for a mission for the sensor-laden platform.
He settled on building a continuous optical densitometer for his biology colleagues. Bacterial cultures become increasingly turbid as the grow, and measuring the optical density (OD) of a culture is a common way to monitor its growth phase. This is usually done by sucking up a bit of the culture to measure, but [Chinna] and his team were able to use the hacked fitness band’s heartrate sensor to measure the OD on the fly. The tracker fits in a 3D-printed holder where an LED can shine through the growing culture; the sensor’s photodiode measures the amount of light getting through and the raw data is available via the tracker’s Bluetooth. The whole thing can be built for less than $20, and the plans have been completely open-sourced.
We really like the idea of turning these fitness bands into something completely different. With the capabilities these things pack into such a cheap and compact package, they should start turning up in more and more projects.
The holidays bring us many things. Family and friends are a given, as is the grand meal in which we invariably overindulge. It’s a chance for decades old songs and movies to somehow manage to bubble back up to the surface, and occasionally a little goodwill even slips in here or there. But perhaps above all, the holidays are a time for every retailer to stock themselves to the rafters with stuff. Do you need it? No. Do they want it? No. But it’s there on display anyway, and you’re almost certainly going to buy it.
Which is precisely how I came to purchase a two pack of Bluetooth Low Energy (BLE) “trackers” for the princely sum of $10 USD. I didn’t expect much out of them for $5 each, but as this seemed an exceptionally low price for such technology in a brick and mortar store, I couldn’t resist. Plus there was something familiar about the look of the tracker that I couldn’t quite put my finger on while I was still in the store.
That vague feeling of recollection sent me digging through my parts bin as soon as I got home, convinced that I had seen something among the detritus that reminded me of my latest prize. Sure enough, I found a “Cube” Bluetooth tracker which, ironically, I had received as a Christmas gift some years ago. Putting them side by side, it was clear that the design of these “itek” trackers took more than a little inspiration from the better known (and five times as expensive) product.
The Cube was a bit thicker, but otherwise the shape, size, and even button placement on the itek was nearly identical. Reading through their respective manuals, the capabilities also seemed in perfect parity, down to being able to use the button on the device as a remote camera control for your smartphone. Which got me thinking: just how similar would these two devices be internally? Clearly they looked and functioned the same, but would they be built the same as well? They would have to cut costs somewhere.
Determined to find out how a company can put out what for all the world looks like a mirror image of a competitor’s device while undercutting them by such a large margin, I cracked both trackers open to get a bit more familiar with what makes them tick. What I found on closer inspection of these two similar gadgets is perhaps best summarized by that age old cautionary adage: “Don’t judge a book by its cover.”
Continue reading “A Cloned Bluetooth Tracker Meets Its Maker”
Getting kids interested in programming is all the rage right now, and the UK is certainly taking pole position with its BBC micro:bit, just recently distributed to every seventh-grader in the land. Germany, proud of its education system and technological prowess, is caught playing catch-up. Until now.
The Calliope Mini (translated here) is essentially a micro:bit clone, but one that has learned from the experience of its spiritual forefather — the connection points are spread around the outside of the board where the crocodile clips won’t accidentally touch each other.
Not content to simply copy, the Calliope also adds additional functionality. A microphone and speaker are integrated onboard, as is a Grove-style I2C connector. They’ve even added a TI DRV8837 H-bridge motor driver, so students could make a rolling robot straight out of the box.
Continue reading “Germans React To UK’s Micro:bit”
[Mikhail] sent us a teaser video for a hack he’d done (embedded below). He takes a Bluetooth LE fitness tracker dongle and reflashes it spit out the raw accelerometer data and trigger events. He then wrote a phone app that receives the data and uses the device as an alarm, an on/off switch, a data-logging device, and more.
We thought it was cool enough that we asked [Mikhail] for more detail, and he delivered in spades! Inside the device is a Nordic NRF51822, their ARM Cortex + Bluetooth chip, an accelerometer, and a bunch of LEDs. [Mikhail] mapped out the programming headers, erased the old flash, and re-filled it with his own code. He even added over-the-air DFU re-flashing capability so that he wouldn’t have to open up the case again.
Continue reading “Custom Firmware Unlocks Fitness Tracker”
Implementing a Bluetooth Low Energy (BLE) device from scratch can be a daunting task. If you’re looking for an incredibly detailed walkthrough of developing a BLE project from essentially the ground up, you’ve now got a lot of reading to do: [Jocelyn Masserot] takes you through all the steps using the ARM-Cortex-M0-plus-BLE nRF51822 chip.
The blog does what blogs do: stacks up in reverse-chronological order. So it’s best that you roll on down to the first post at the bottom and start there. [Jocelyn] walks you through everything from setting up the ARM compiler toolchain through building up a linker script, blinking an LED, flashing the chip, and finally to advertising your device to your cell phone. It’s a lot of detail, but if you’re doing something like this yourself, you’re sure to appreciate it.
Of course, all the code is available for you to
crib peruse on [Jocelyn]’s GitHub. And for yet more background reading on BLE, check out the Hackaday Dictionary.