Wouldnt it be sweet if you could have your micro play-back complex things, over audio for an extremely low cost? Imagine replacing that one i/o line that used to drive an led, be able to reproduce the human voice and exclaim “Hello world”, This can be useful in projects where you would like to add some human interface, but an lcd would be too bulky / to slow.
PWM audio generation with an AVR - [Link]
There are many versions of DTMF decoders outside the Internet, but all are doing pretty the same – decoding dual tone codes in to digits, that can be later interpreted by microcontroller. This device uses an integrated decoder chip MT8870DE which decodes all 16 DTMF tone pairs in to 4 bit code.
AVR Microcontroller reads these codes and outputs them to LCD as characters. DTMF receiver stores last 234 received digits in EEPROM that can be viewed by scrolling an LCD character line. DTMF Decoder also can be connected to PC via RS232 interface. So each time TDMF signal is received it sends digit to Terminal. Program is written by using free WinAVR GCC compiler tools. [via]
AVR DTMF decoder based on MT8870DE - [Link]
This is an Open Source Application which allows you to use your Oscilloscope as a text based display device. The code is currently targetted for the Dutchtronix AVR Oscilloscope Clock hardware but could be easily ported to an alternate platform consisting of an AVR and some form of a DAC. The Scope Terminal displays 12 lines of 20 characters each. There is also a line showing the current time (it’s a clock hardware after all). Configuration is possible using a “Command Mode” where you can use a terminal (usually a PC) to set options (currently Time Change and Baudrate change are supported). This alternate application can be downloaded to the AVR Oscilloscope Clock using the built-in bootloader; no AVR programmer required. Full Source Code is available on the website.
AVR Scope terminal – Oscilloscope terminal! - [Link]
This is a portable battery powered Rogue-like video game- The dungeons of Doom. The game runs on Atmega32 microcontroller. So it can be plugged to any TV set with NTSC decoder. AVR to TV interfacing is done with well known video DAC made of 3 resistors and is tuned to 75Ω TV input resistance. The whole project including 9V battery fits in a box for Altoid mints. Project source code can be downloaded here. Game code is far not complete, like only one monster implemented, also player inventory has no different weapons and items. But I guess there is still some fun to se some action on TV screen. [via]
AVR based Rogue video game - [Link]
With this circuit you can drive a unipolar stepper motor. It operates in full step mode. You can get a stepper motor from an old 5.25 disk drive. The AVR2313 micro controller controls the pulses for the stepper motor. The pulses are amplified by the ULN2003 driver. The driver accepts 5V inputs, the output for the driver is up to 30V so you can connect an stepper motor of up to 30V. With the two push switches you can drive the stepper motor CW or CCW.
AVR Stepper Motor Driver - [Link]
If you go to AVR site and open an AVR application note AVR053 you will notice that there are different RC oscillators installed in to AVR chips during history. Simply speaking each new version of oscillator introduces better features and improvements. But is it really truth? ChaN has made interesting research on these oscillator version. He simply tested output signal with fixed width and measured timing fluctuations of it. And he found out, that RC generator frequency slowly fluctuates during time.
AVR internal oscillator jitter research - [Link]
This is another great project that came from dutchtronix. This time oscilloscope is used as text terminal. This seems to be quite practical project. Imagine situation that you need to debug microcontroller code. The easiest way is to use terminal which is usually a computer. But computer isn’t always on your workbench. So why not to use an oscilloscope as terminal?
If you already have the Dutchtronix AVR Oscilloscope Clock, you now also have the Dutchtronix AVR Oscilloscope Terminal which works on same hardware, only firmware needs to be uploaded. Terminal is capable to output 12 lines with 20 characters each. It also includes all ASCII character set, automatic scrolling, flashing cursor, multiple baud support, etc.
Use oscilloscope as terminal output - [Link]
“The Open Source project Liberlab aims to help democratize educational scientific experimentation through the creation and use of a DIY digital lab at a very low price ( ~ 15 €/$). Liberlab can also be used to learn about robotics, automation, human-machine interface or interactive arts.”
Liberlab – Open source data acquisition and control - [Link]
There may be some situations when it is hard to use a tachometer only because it is impossible to read revolutions per minute mechanically. The only way is to read RPM without touching rotating shaft. This great design was constructed by Ibrahim Kamal who used an IR signal to transmit and receive it reflected from reflective stripe fixed to rotating shaft. Device is controlled by AT89S52 microcontroller which counts reflected pulses and displays value on LCD. RPM counting algorithm uses last three times between pulses and this way constantly gives instant RPM value. RPM meter consists of two parts: microcontroller board and IR proximity sensor connected to microcontroller board via simple 4 wire cable. Project files are available for download in a single zip.
Contact-less tachometer counts up to 99kRPM - [Link]
DiSEqC-Switch is widely used in individual satellite systems to connect up to 16 satellites to one receiver using cascading method. This switch uses other cheap DiSEqC-Switches ver1.0 with four satelite heads each or simply connects directly to satelite heads and this way acts as simple switch. [via]
Connect up to 16 satellites to one receiver with AVR DiSEqC switch - [Link]