Presentation Remote - 2013
This device is helpful whenever you give a presentation. Presentation remotes are not available everywhere, so you may need to bring one with you. And since I hadn't had any, I've made one.
The transmitter contains 3V CR2032 battery, Attiny13 processor, 433Mhz transmitter module, 4 buttons and a lot of glue:) The microcontroller is not in sleep mode, instead, the battery is entirely disconnected from the circuit and is connected only by pressing one of the buttons. This makes the circuit consume literally nothing in standby, but also introduces some instability in power delivery during button bouncing. Sacrificing the minuscule current consumption of Attiny13 in power-down mode might, in the end, be a better alternative.
The buttons on the transmitter represent keys on a regular keyboard, namely: left and right arrows for the previous and next slide, F5 for the start of a presentation, and B for pause.
The receiver is made out of a 433Mhz receiver module and Attiny85. The microcontroller emulates a common USB keyboard (using a V-USB library) and if the signal from the 433Mhz receiver module matches one of the 4 programmed patterns (each button on the transmitter corresponds to a specific pattern), it emulates a key press.
Firmware and schematic: here
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