Sound based Data Transmission

DTMF have been used to transfer data through sound, however it limits the data rates. In this project they have used a speaker and a microphone system to transmit the data generated. The data is generated using a PS/2 remote which is then processed by the microcontroller and the audio signal is fed to a speaker. The sound is detected by the microphone attached on the user side which is then processed and displayed on the LCD attached to the receiver side. The TX-MCU samples DATA on the falling edge of CLK to build a data packet representing the key that was pressed, then transmits the packet as a combination of two alternating on/off tones (one at 8 kHz, another at 5 kHz) over the speakers, where one tone represents CLK and the other represents DATA. The current design uses a very simple protocol called On-Off Keying on two tones. Upgrading the code to use a more sophisticated protocol would increase the data rate. The change in speaker and microphone specifications might also increase the range of the system. Continue reading

A Sound Follower Robot

The name of the robot is Clap-E which is a sound follower robot and follows you as long as you are clapping. It was designed by students of Cornell University as their final year project. It’s insensitive to normal human voice and other noises in the environment, however if you are able to produce a noise as sharp as clapping, then it will follow you.  The bot is able to detect the direction of source of clap by applying ‘time of arrival’ principal.  The time of arrival between two waves is calculated and using basic trigonometry the position is identified The hardware comprises of two circuits mainly sensory circuitry and a servo driver circuit.  The sensor circuits comprised of microphone as the main sensor device. A total of three microphone were placed at vertices of an equilateral triangle. The bot is very sensitive to clap sounds, since sound is detected using interrupts. However, if the clap is more than 2 meters away from the robot, the latter cannot respond to the sound due to the quality of sensors with low… Continue reading

The Cheeky Talking Calculator

Anyone here who love to deal with mathematical solutions, please rise up your hand! Well, for those who have no interest in the mathematics, calculating could be a horrible nightmare to you. According to the history of calculator, the abacus was the very first arithmetic invention used by ancient merchants in Asia and Africa. Believe it or not, the abacus is still being used by many people, especially in China! The World’s first all-electric compact calculator is the Model 14-A calculator, which is a proud product from The Casio Computer Company, Japan in 1957. Four years after that, the world’s first all-electronic desktop calculator, the Bell Punch/Sumlock Comptometer ANITA was announced. Later on, the designation of calculator is becoming more advanced, where its applied the nickel-cadmium batteries and liquid crystal displays onto the modern calculators. Yet, majority of the calculators in present days are equipped with tiny solar panel on the top left corner! Let’s go back to the topic again. The talking calculator is a user-friendly calculator. It based on an ATmega88 microcontroller. It features the four basic operations:… Continue reading

Playing real music with Arduino

Usually in electronic projects people choose to use low quality sounds like ISD chips with 8 kHz sampling rate, direct PWM, or end up with MP3 decoders. Las option is to play uncompressed audio files from SD/MMC card via DAC. Such solution can give good sampling rate and good quality especially when sound is filtered and amplified with op-amp. This project is set up around Arduino board. It takes wave files from CD/MMC card and plays them asynchronously as an interrupt. So there are resources left for additional tasks between them. It can play 22 kHz, 16 bit mono wave files of any size. Files are stored in FAT18 formatted media card – so it is easy to upload new files via standard card reader. All files and libraries are downloadable or as usually you can order a kit to enjoy the music. Over all project is well described – I recommend to read even if you aren’t going to build one. There are some good materials about audio sampling and interfacing SD/MMC cards with arduino. Continue reading

AVR controlled Interactive rhythm sequencer

This is something interesting and may engage you for some time. This project is so called Rhythm Ring which actually is a musical device that can play rhythms and beat patterns by touching sensors with fingers or metal ball bearings. Each sound is lead by bright LEDs that makes effect even more attractive. When the device is turned on, it begins at a pre-defined position on the circle and sweeps along the tracks in a circular motion. As it sweeps around the circle, it keeps track of the current position along the circumference of the circle. In the center of the board, there are 32 green LEDs arranged in a circle with only one of the LEDs lit at a time, showing the current position. Sequencer has speed control buttons where you can change sweep speed and this way speed up the rhythm. Project very well described (students have to do this) but once made this thing may keep you busy for several hours. Continue reading

Generate a real time video signal along with the sound on AVR

Jonathan have sent us a link to amazing embedded project. Generating sound and VGA video signal on a single AVR chip is really challenging task. Everything is time critical here. AVR Atmega88 microcontroller is clocked at 20MHz and so it generates 45 full VGA display lines at almost 60Hz frame rate. Sound is generated during VGA horizontal blanking periods. That gives a sampling rate of 31496kHz which is enough for good chip-sound quality. Sound player is capable to play four sound channels. And all that beauty is programmed in pure assembly language for best performance. Project files can be downloaded here. Continue reading