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 unitm 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.
Building a digital light meter with a calibrated LDR - [Link]
Like many people, I have fairly diverse taste in music. My media library holds tracks from Bach, Beethoven, Billy Joel, Bonobo, Brent Lamb, Brahms, Brian Hughes, and the Bee Gees (to name just the “B” section). I love variety. The trouble is, all of these different genres tend to require slightly different volume settings. Worse still, in the case of some classical music, you can get quite a wide range of volumes within a single piece (e.g. O Fortuna). So if I hook up my BlackBerry and set it to shuffle, I find myself having to continually adjust the volume knob – either because I can hardly hear the current track, or because my neighbors are about to come banging on my door.
Well, I’m not the first one to have this problem. Nor am I the only one to attempt to solve it. In fact, it’s already been solved. As you may know, there are plenty of software solutions out there for so-called volume leveling. But before the advent of the BlackBerry, or the personal computer, there was the analog compressor.
AVR Audio Compressor – digital volume leveler - [Link]
I2C (also referred as IIC or TWI) is widely used interface in embedded applications. Two wire bus initially was used by Philips and become a standard among chip vendors. I2C bus consists of two lines called Serial Data Line (SDA) and Serial Clock Line (SCL). Communication is relatively fast and short distance mainly used to communicate between sensors, RTC, EEPROM, LCD. I2C protocol allows up to 128 devices connected to those two lines where each of them has unique address. Communication between devices is master and slave based. Master generates clock signal, initiates and terminates data transfer.
Programming AVR I2C interface - [Link]
Gabotronics’ Xminilab is a mixed signal oscilloscope with an arbitrary waveform generator in a DIP module. It measures only 3.3 x 1.75 inches, and can be mounted directly on a breadboard. The Xminilab can also be used as a development board for the AVR XMEGA microcontroller. [via]
This remarkable new product features a mixed signal oscilloscope for simultaneous sampling of analog and digital signals. Some tech features:
- Advanced Trigger: Normal / Single / Auto, with rising or falling edge and adjustable trigger level.
- Meter Mode: Average, Peak to peak and Frequency readout.
- XY Mode (Plot Lissajous patterns or see the phase difference between two waveforms).
- Spectrum Analyzer with different windowing options and selectable vertical log.
- Horizontal and Vertical Cursors with automatic waveform measurements.
- Arbitrary Waveform Generator with Frequency Sweep.
- Display options: Persistence, Different grid options, and more.
An oscilloscope for 64 dollars - [Link]
Phillip also designed a cable version of this project that is available on his site.
Ultra-small vusbtiny AVR programmer - [Link]
Atmel launches digital audio development system – [via]
Atmel Corporation has announced a complete hardware and firmware digital audio solution aimed at simplifying the design of digital audio equipment for consumer, automotive and industrial applications. Based on the Atmel’s AVR UC3 microcontrollers, the Digital Audio Platform is specifically tailored for audio applications such as USB docking stations for smartphones and media players.
The platform comprises dedicated microcontrollers, evaluation kits and firmware IP. The firmware IP includes control and streaming interfaces for popular smartphones and portable media players as well as MP3, WMA and AAC decoders, USB protocol stacks, and a complete file system to allow designers to utilize mass storage devices such as USB flash disks and SD cards. The Digital Audio Platform is ideal for applications including docking stations, USB mass storage, SD card playback, car stereos, USB speakers, microphones, and various voice and music equipment.
Atmel launches digital audio development system - [Link]
Please welcome ArduPilotMega 2.0! – DIY Drones. Jordi writes – [via]
APM 2.0 is the culmination of almost a year of hard work. We wanted to make it perfect and we finally have it, we are pushing the limits of AVR and Arduino. I’m sure you will love it, and it’s designed to cover all the DIY community expectations (including those that are not so DIY and are only interested for something that doesn’t require soldering skills).
ArduPilotMega 2.0! - [Link]
For a while now, my friends and I have been brewing beer at my house. I was inspired by an old Sparkfun tutorial about a bubble logger for Nate’s terrible wine. I figured that while logging bubbles is interesting and all, wouldn’t it be more useful to have real-time information on the fermentation process? I basically copied the optical gate method of counting bubbles, added a sensitive pressure sensor, and an AVR development board (Yes, Arwen, that’s your old TekBots board! ).
Homebrew bubble counter - [Link]
USBasp is a USB in-circuit programmer for Atmel AVR controllers. It simply consists of an ATMega48 and ATMega88 an ATMega8 and a couple of passive components. The programmer uses a firmware-only USB driver, no special USB controller is needed.
- Works under multiple platforms. Linux, Mac OS X and Windows are tested.
- No special controllers or smd components are needed.
- Programming speed is up to 5kBytes/sec.
- SCK option to support targets with low clock speed (< 1,5MHz).
USBasp – USB programmer for Atmel AVR controllers - [Link]
This simple COM PORT based AVR atmega Programmer will allow you to painlessly transfer hex programs to most ATMEL AVR microcontrollers without sacrificing your budget and time. It is more reliable than most other simple AVR programmers available out there and can be built in very short amount of time.
AVR programmer consists of in-circuit serial programmer (dongle) and small pcb with a DIP socket where you can fit your microcontroller and have it quickly programmed.
AVR Serial Port Programmer - [Link]