A person who is deaf can’t hear sound, but that doesn’t mean they can’t feel vibrations. For his Hackaday Prize entry, [Alex Hunt] is developing the Shakelet, a vibrating wristband for that notifies hearing impaired people about telephones, doorbells, and other sound alerts.
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:
Continue reading “Hackaday Prize Entry: Shakelet”
[João Ribeiro] is an electronics engineer by day, but in his free time he likes to ply his trade on everyday items. Recently he’s been integrating his own microcontroller network to unlock and start his car via RFID. In addition to the joy of pulling apart the car’s interior, he spent time designing his own uC breakout board and developing an RFID reader from a single chip.
He’s working with a 1988 Mercedes that has very little in the way of electronics. It sounds like the stock vehicle didn’t even include a CAN bus so the prelude to the RFID hack had him installing a CAN bus network made up of two microcontrollers. One reads the velocity and RPM while the other displays it on the tachometer. When he began the tag-based entry system he used an RFID reader module for prototyping, but eventually built his own reader around the TRF7960 chip. This included etching his own receiver coil which was mounted in the side-view mirror bracket. To unlock the doors he holds the bracelet up to the mirror and the vehicle lets him in. The video after the break starts with a demonstration of the completed project and moves on to some build videos.
We certainly like the idea of using a bracelet rather than implanting the tag in the meaty part of your hand.
Continue reading “Wristband RFID unlocks car door and starts engine”