BLE sensor coins can be had for pocket change, if you know where to look.
If you trade a small stack of quarters in for the equivalent BLE denomination, you can walk away with a nifty little disc-shaped device, barely bigger than a dollar.
These generic devices of design origins often unknown certainly look like they share a bit of a family tree!
What I can only assume is perhaps an ecosystem of electronic tags based upon a reference design of days gone by, these little boards can be amusing to poke about with.
The fun ones are loaded up with a Nordic Semiconductor Bluetooth-capable MCU (usually an nRF51 Series), they will often also feature a few generic I2C sensors — proximity, ambient light and acceleration are common.
Cruising along on a coin cell clipped to the rear or the module, you can usually coax some readings out of the bluetooth connection with the handy Nordic mobile phone apps.
nRF Toolbox is especially useful for "phreaking" BLE descriptors of unknown function.
These are fun devices, but as I've mentioned, they can come with a few caveats.
You're often left without a schematic, and if you can find one, it can be for a different board variation as well. Sometimes you're not even going to get the same thing you ordered.
The rayBeacon is a glimmer of hope for those looking to boost their BLE designs, with a board that boasts both power and style.
Designed by Mike M. Volokhov, the rayBeacon is a brilliant bit of engineering. Seen below, complete with its perforated break-away tabs, used for programming and additional development, it's evident that there's some serious signal routing going on under the solder mask of this board.
Nordic are turning out some powerful BLE-capable chips, that are no strangers to the Hackster pages. With the powerful ARM Cortex M4 core found in the nRF52 range, it's pretty easy to see why they are so popular with makers. For a comprehensive view of the full lineup of nRF52 parts, check out Nordic's infocenter page.
With the near-center of the coin occupied by either the Nordic Semiconductor nRF52833 or nRF52840 BLE MCU parts, the rest of the layout is a bit of a passive parts party.
Thankfully, there are some telling PTH pads that indicate that the party is only just getting started. But before we get too carried away, let's look at the gorgeous graphical datasheet that Volokhov has turned out below for the rundown on what's included.
The tear off adapter is a brilliant idea. Not only does it route out signals found on the 2x4 1.27mm pitch on-board header to a more breadboard friendly 2.54mm pitch, once torn away, it still serves its purpose as an adapter. By featuring an additional 1.27mm header, to allow it to plug back into the main board, it serves as a handy debug or extension header, rather than scrap. That's a really nice touch that helps to reclaim some value from otherwise wasted FR4.
Two features you wouldn't normally see on the various unbranded beacons from AliExpress et al, that are included on the rayBeacon really make it stand out for some potential extra fun.
- The inclusion of the NFC antenna connection socket is a great idea, given the functionality is built into the nRF52 silicon.
- The call out for the infrared LEDs caught my eye, even if they themselves wouldn't!
Instantly, I can see a potential use case of a "BLE Beacon IR Blaster," perfect for streamlining home cinema setups perhaps? I'm sure you can think of many more fun applications for something that can converse with both Bluetooth and infrared devices!
There's a lot of emphasis on accessibility to the signals routed to that connector, and for good reason, it's the primary expansion method for the rayBeacon hardware, and digging into the bitbucket repo shows up two add-on expansion boards, that Volokhov is referring to as "slices."
These slices serve to expand the functionality of the core rayBeacon module, and it's an appealing way of managing the balance of function and form that can often plague space-constrained projects.
Not every application will require all the bells and whistles, so why bother cramming potentially unused, and even potentially wasteful resources into a design, when you can select them when required, by snapping on the appropriate slice!
The first slice to be served up is the aptly named "Harvester."
This board is clearly aimed at longer term deployments, and serves to siphon power from its surroundings, using a number of techniques that are collectively classed as "Energy Harvesting."
Featuring a SPV1050 energy harvesting IC from ST Microelectronics, this miniature implements the MPPT functionality required to enable it to select from a bevvy of suitable power sources, including photovoltaic (solar) and TEG (thermoelectric generator) sources.
TEG is a really interesting option, if the designer can get the thermal mechanics of a design correct. In essence, it uses the same Peltier junctions that are found in the solid state cooling modules some of us have played with.
A lesser known fact about Peltier junctions is that not only do they develop a temperature differential when power is applied to them, but, like a thermocouple, they are able to generate a potential voltage in response to a thermal gradient!
If your deployment is tracking temperature, this is a very appealing option, as you may be able to power your device eternally, with just a heatsink and the appropriate TEG array!
Harvester also brings the native USB connection of the nRF52 out to a microUSB connector, should the user not wish to solder wires to the exposed signal test points on the rayBeacon main PCB module.
Orient follows in the suitably simple naming convention of its sibling slice, and does very much as its name implies — featuring all the bits your board needs to get its bearings.
With both a ST Microelectronics LSM303AGR electronic compass and a BMG250 gyroscope, this quarter-sized puck has no problem computing your quaternions. Pitch roll and yaw? Yawn, it can do that before it gets out of bed!
This is a neatly planned out project. The rayBeacon core is a powerful BLE platform already, and the slices allow it to be tailored to a number of scenarios out of the box. What is more, the open nature of the project and use of stacking headers should make it a breeze for anyone to modify it to any specific uses they might have!
The entire project is publicly available over on the rayBeacon BitBucket for those looking to start out with their own BLE beacon stack.
Follow Volokhov on Twitter for more details as he publishes more project updates!