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Category Archives: AVR Projects

Nickelphone: Coin-based Midi Keyboard

Posted on October 29, 2013 by R-B Leave a comment

Tyler Bletsch’s Nickelphone is a coin-based music keyboard that has 15 nickels and 10 pennies arranged on a traditional 25-key piano-style layout and act as touch sensors. It can emit simple square wave tones through an onboard piezo buzzer, but its primary use is as a MIDI keyboard, so it can drive a full synthesizer (like FL Studio on PC). Tyler used an ATmega644 microcontroller for his project so that he would have enough I/O pins (each key uses its own I/O pin) for the 25 keys.

DIY wristwatch using Atmega328P

Posted on September 27, 2013 by R-B Leave a comment

Zak Kemble from England has shared his digital wristwatch buildon his blog. It is a very neat and clever design using the Atmega328P microcontroller and a 1.3″ OLED for display. The watch is powered by a 150mAh LiPo battery which can be charged via USB. The onboard battery charging circuit uses Microchip’s MCP73832 device. The ATmega328P uses its internal 8MHz oscillator and runs on 2.5V derived from a linear regulator. Time-keeping is done with the DS3231M RTC chip. With 32K of program memory, Zak has implemented many other cool features besides displaying time and date, such as alarm, stopwatch, animation,

Proximity sensing for mobile phones SAR requirements

Posted on September 21, 2013 by R-B Leave a comment

Research in to the long term health effects from exposure to radio frequency energy has been ongoing over the past two decades. As a result of this research the FCC and other telecommunications agencies have adopted limits for safe exposure to radio frequency (RF) energy. These limits are referred to as the Specific Absorption Rate (SAR), which is the measure of the amount of radio frequency energy absorbed by the body when using a mobile phone or other wireless device. The FCC and other agencies require that manufacturers of wireless devices comply with these limits for safe exposure. In order

Chirp: An open source plant watering alarm using Attiny44A

Posted on August 1, 2013 by R-B 3 comments

Your favorite plants need plenty of water to grow. If you keep forgetting to water your house plants you might be interested in this plant watering alarm device called Chirp. Chirp uses capacitive humidity sensing technique to measure the moisture level in the soil and alerts the user through short chirps when it is time to water the plant. Based on the amount of ambient light detected by the on-board light sensor, Chirp detects day and night condition. It is very considerate and remains silent during the night time. The project uses ATtiny44A and is licensed under CERN Open Hardware

1Hz to 10MHz frequency meter using ATtiny2313

Posted on March 25, 2013 by R-B 2 comments

This AVR-based Frequency Meter is capable of measuring frequencies from 1Hz to 10MHz with 1 Hz resolution. The hardware of this project consists of seven 7-segment displays, AVR ATtiny2313 uController, and a few transistors and resistors. The AVR counts input pulses for a precise 1 second interval (generated using the built-in Timer) and displays the result on the multiplexed seven segment LED displays.

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