To tackle the difficulty of discriminating between the different sounds from different sources, [Alex’s] wants to attach little sound sensors directly to the sound emitting devices. The sensors wirelessly communicate with the wristband. If the wristband receives a trigger signal from one of the sensors, it alerts the wearer by vibrating. It also shows which device triggered the alert by flashing an RGB LED in a certain color. A first breadboard prototype of his idea confirmed the feasibility of the concept.
After solving a few minor problems with the sensitivity of the sensors, [Alex] now has a working prototype. The wristband features a pager motor and is controlled by an ATMEGA168. Two NRF24L01+ 2.4 GHz wireless transceiver modules take care of the communication. The sound sensors run on the smaller ATTiny85 and use a piezo disc as microphone. Check out the video below, where Alex demonstrates his build:
A robot to explore the unknown and automate tomorrow’s tasks and the ones after them needs to be extremely versatile. Ideally, it was capable of being any size, any shape, and any functionality, shapeless like water, flexible and smart. For his Hackaday Prize entry, [Alberto] is building such a modular, self-reconfiguring robot: Dtto.
To achieve the highest possible reconfigurability, [Alberto’s] robot is designed to be the building block of a larger, mechanical organism. Inspired by the similar MTRAN III, individual robots feature two actuated hinges that give them flexibility and the ability to move on their own. A coupling mechanism on both ends of the robot allows the little crawlers to self-assemble in various configurations and carry out complex tasks together. They can chain together to form a snake, turn into a wheel and even become four (or more) legged walkers. With six coupling faces on each robot, that allow for connections in four orientations, virtually any topology is possible.
Each robot contains two strong servos for the hinges and three smaller ones for the coupling mechanism. Alignment magnets help the robots to index against each other before a latch locks them in place. The clever mechanism doubles as an ejector, so connections can be undone against the force of the alignment magnets. Most of the electronics, including an Arduino Nano, a Bluetooth and a NRF24L01+ module, are densely mounted inside one end of the robot, while the other end can be used to add additional features, such as a camera module, an accelerometer and more. The following video shows four Dtto robots in a snake configuration crawling through a tube.
While faking BLE advertising beacons using an nRF24L01+ module is nothing new, it’s become a heck of a lot easier now that [Pranav Gulati] has written some library code and a few examples for it.
[Pranav]’s work is based on [Dmitry Grinberg]’s epic bit-banging BLE research that we featured way back in 2013. And while the advertisement channel in BLE is limited in the amount of data it can send, a $1 nRF24 module and a power-thrifty microcontroller would be great for a battery-powered device that needs to send small amount of data infrequently for a really long time.
We’re not 100% sure where [Pranav] is going to take this project. Honestly, the library looks like it’s ready to use right now. If you’ve been holding off on making your own BLE-enabled flock of birds, or even if you just want to mess around with the protocol, your life has gotten a lot easier.
nRF24L01+ PA/LNA module specs look great on paper. Wireless communication up to 1000m in a small package readily available from a variety of cheap sources in China? The hard work of software connectivity already done by a variety of open source projects? Sounds great! But if you mashed BUY and are getting maybe 1% of that range, don’t worry because thanks to these clear directions, they can be fixed.
[Oitzu] in Germany wrote in to let us know about a series of short but very informative blog posts in which he describes building a series of solar-powered, networked birdhouses with the purpose of spying on the life that goes on within them. He made just one at first, then expanded to a small network of them. They work wonderfully, and [Oitzu]’s documentation will be a big help to anyone looking to implement any of the same elements – which include a Raspberry Pi in one unit as a main gateway, multiple remote units in other birdhouses taking pictures and sending those to the Pi over an nRF24L01+ based radio network, and having the Pi manage uploading those images using access to the mobile network. All with solar power.
Hackers love to monitor things. Whether it’s the outside temperature or the energy used to take a shower, building a sensor and displaying a real-time graph of the data is hacker heaven. But the most interesting graphs comes from monitoring overall power use, and that’s where this optically coupled smart-meter monitor comes in.
[Michel]’s meter reader is pretty straightforward. His smart wattmeter is equipped with an IR LED that pips for every watt-hour consumed, so optical coupling was a natural approach. The pulse itself is only 10 ms wide, so he built a pulse stretcher to condition the pulse for a PIC microcontroller. The PIC also reads the outside temperature with a DS18B20 and feeds everything to the central power monitor, with an LCD display and a classic Simpson meter to display current power usage. The central monitor sends the power and temperature data to Thingspeak, along with data from [Michel]’s wood-stove monitor and a yet-to-be-implemented water heater monitor.
[Michel] is building out an impressive suite of energy and environmental monitors for his Quebec base of operations. We’re looking forward to seeing how he monitors that water heater, and to see what other ideas he comes up with.
Who needs the Internet of Things? Not this interactive, sound playback blanket! Instead, hidden within its soft fuzzy exterior, it makes use of a NRF24L01+ module to speak directly with its sound server.
The project was built for a school, and let the students record whatever sounds they think are important into a Raspberry Pi. Then, the students assembled the physical felt blanket, with the sensors sewn inside, and could play back their favorite sounds by clambering all over the floor. It’s a multi-sensory, participatory, DIY extravaganza. We wish we did cool stuff like that in grade school.
We like DIY music controllers a lot, and this simple setup stands to be more useful than just blanket-making. And in this age of everything-over-WiFi, it’s refreshing to see a straight-up 2.4 GHz radio build when that’s all that was necessary.
[Dan]’s complaint that the NRF24 modules could only reach 3m or so strikes us as strange though. Perhaps it’s because of all of the metal in close proximity to the NRF24’s antenna?