This project allows one to use a universal IR remote to control an AVR based Etch A Sketch. For display, we use the Nokia 3310 LCD ($10 from SparkFun.com). The Etch A Sketch functionality is simply the ability to draw in a straight line up, down, left, right. The purpose of this project was to demonstrate the improvements to CC Dharmani’s NOkia 3310 library that allows per pixel access using a pixel buffer. The improved version has been included in the source of this project *
AVR based Etch A Sketch with Nokia 3310 LCD – [Link]
SD / MMC cards support a SPI mode. By connecting it to an AVR’s SPI port, it can be used for general storage relatively easy. Here I demo the use of an SD / MMC card as general storage for electronics projects. I am using it with a 1MHz Atmel AVR atmega8, standard 2GB microSD card with adapter sleeve, and using a PWM port as a cheap DAC for sound output. I first loaded the SD card with pre-recorded sounds at 8KHz and 8-bit unsigned linear. I then read them in real time from the SD card and write the values to the OCR so that they set the duty cycle on a PWM port. I use a simple RC low pass filter as a cheap DAC (Digital to Analog Convertor) that is output to a speaker.
Use an SD or MMC card on your next AVR project - [Link]
Last week on hack-a-day I saw their post on an LED Menorah that was powered by a 9v battery with the lights controlled by dip switches. I thought to myself, “gee, that’s not a very creative design”. There was redemption in the minimalist designs linked too showing a menorah soldered to a tiny2313 and one soldered to an LM2913, both without a circuit board.
LED Menorah powered by AVR tiny13 – [Link]
Here is my experiment with i2c bus for interfacing serial EEPROM (24C256) and RTC (DS1307) using AVR microcontroller ATmega128. The circuit is also provided with an RS232 port for connecting with PC to send commands for reading/writing EEPROM or setting date/time in RTC (Click on images to enlarge them).
Interfacing RTC & serial EEPROM using i2c bus, with ATmega128 uC – [Link]
For those who are trying to make AVR kit at home, an AVR programmer which can be simple to make will be really useful, as it’ll avoid buying the programmer!! Here I’m giving a few webpage links on how to make a programmers yourself.
DIY AVR Programmers - [Link]
Here is a very simple project of controlling a small DC-motor (taken from an old personal cassette player) with ATmega8. The ATmega8 is having three PWM channels, out of which two are used here. PWM waveforms are fed to MOSFET (RFD3055) H-bridge. Here, direction is controlled using a two-position toggle switch and speed of the motor is controlled by two push-buttons, one for increasing the speed and other for reducing.
Simple PWM DC motor control using MOSFET H-Bridge with AVR ATmega8 - [Link]
dangerousprototypes.com writes: [via]
Here’s a good tutorial from ExtremeElectronics.co.in explaining the types of stepper motors, their uses, and how to interface them with an AVR microcontroller.
It includes the xstepper code library for use with the AVR Atmega16, and demonstrates how to interface the MCU and the motor using a ULN2003A high-voltage high-current Darlington transistor array.
This tutorial is comprehensive and provides beginners with the theory and sample code to get started with a simple stepper motor project.
Stepper motor tutorial – [Link]
rbw writes – [via]
Pulse Width Modulation (PWM) is a technique widely used in modern switching circuit to control the amount of power given to the electrical device. This method simply switches ON and OFF the power supplied to the electrical device rapidly. The average amount of energy received by the electrical device is corresponding to the ON and OFF period (duty cycle); therefore by varying the ON period i.e. longer or shorter, we could easily control the amount of energy received by the electrical device. The Light Emitting Diode (LED) will respond to this pulse by dimming or brighten its light while the electrical motor will respond to this pulse by turning its rotor slow or fast.
Working with Atmel AVR Microcontroller Basic Pulse Width Modulation (PWM) - [Link]
Using an AVR as an RFID tag, Beth writes… [via]
Last time, I posted an ultra-simple “from scratch” RFID reader, which uses no application-specific components: just a Propeller microcontroller and a few passive components. This time, I tried the opposite: building an RFID tag using no application-specific parts.
Well, my solution is full of dirty tricks, but the results aren’t half bad. I used an Atmel AVR microcontroller (the ATtiny85) and a coil. That’s it. You can optionally add a couple of capacitors to improve performance with some types of coils, but with this method it’s possible to build a working RFID tag just by soldering a small inductor to an AVR chip
Using an AVR as an RFID tag - [Link]