Keyboards with extra keys for quick multimedia control are a handy shortcut for geeks who love to listen to music while working on their computers. However, not all keyboards contain those extra keys. The Peng Multimedia Controller project is a DIY USB hardware device that provides shortcut keys for easy media control. It supports the basic media control features such as Next/Previous, Play/Pause and volume control. The project uses Atmega8 microcontroller which communicates with the PC through a software-only implementation of USB using V-USB. While push switches are used for Play/Pause and Next/Previous functions, a linear potentiometer is used for volume control. The casing for the project is custom-designed using 3-D printer.
USB media controller
Measurement of light intensity is a prime necessity in several occasions. The diversity of such needs make their way to various branches of physics and engineering as well as in media. For instance, in engineering, such kinds of measurements are needed to design optimum lighting conditions of a room. In photography, light intensity measurements ensure good quality pictures by determining the right exposure. Wiring a phototransistor or a light-dependent-resistor (LDR) with an analogue LED voltmeter chip like the LM3914 or even to a microcontroller and displaying the ADC values is a pretty simple technique of measuring light intensity. The bad part of this technique is that these simple and amateur-level devices can only measure relative intensity of light and are unable to provide measurements on an absolute scale. However, with a precise knowledge of the transfer characteristic (resistance vs light intensity) of the LDR it is possible to relate the LDR output to the intensity of light in standard unit. In case the LDR characteristic is unknown or unreliable, you can still calibrate the sensor output by using a variable light source and an external reference photometer. This project is about a microcontroller based light intensity meter where an LDR light sensor is calibrated against an external photometer to obtain the intensity of incoming light in the unit of lux. The lux is the SI unit of illuminance and luminous emittance, and measures lumens per square meter (lm/m2). The microcontroller used in this project is ATMega8L and its firmware is written using mikroElektronika’s MikroC Pro for AVR compiler.
AVR based LUX meter
Ond?ej Stan?k, a student of Computer science at Charles University in Prague, the Czech Republic, won first prize in the freestyle category on the RobotChallenge competition in Vienna with this matchbox size line following robot (which he has named PocketBox). The robot is powered with two lithium-ion button batteries and is controlled by the Atmel ATmega8 microcontroller.
Bottom view of PocketBot
In one of my previous posts, I discussed about Sensirion’s SHT11 and SHT75 sensors, which are capable of measuring both temperature and relative humidity. They are digital sensors and provide fully calibrated digital outputs for temperature and relative humidity. I also illustrated how to interface those sensors with a PIC microcontroller. Shawon Shahryiar from Dhaka, Bangladesh shared this project with us where he describes a method of interfacing the HSM-20G sensor to Atmega8 for measuring the ambient temperature and relative humidity. Unlike Sensirion’s SHT series, this is an analog sensor that converts the two ambient parameters into standard output voltages.
Using HSM-20G sensor with Atmega8
This project is from Extreme Electronics that describes an AVR-based (Atmega8) remotely controlled fan regulator. The control commands are received through a DVD player remote control. With three buttons on the remote control, you can turn the fan On and Off and also conotrol the speed. You can also purchase the PCB for this project too.
AVR Fan Regulator Board