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]
I spent some time during Thanksgiving to build an automatic cat feeder but I’m just now getting around to writing something about it. Our cats want to be fed at 6am but I don’t want to get up to do so. This aims to get them fed and back to bed without waking us up! All the good stuff after the break.
Automatic cat feeder – [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]
This instructable is meant to be a more complete explanation than others available online. Notably, this will provide more hardware explanation than is available in the LED Marquee instructable by led555.
GoalsThis instructable presents the concepts involved with shift registers and high side drivers. By illustrating these concepts with an 8×8 LED matrix I hope to provide you with the tools needed to adapt and expand to the size and layout your project calls for.
LED matrix using shift registers – [Link]
One of the biggest hurdles for the mythTV community seems to be providing an IR receiver so that you can use your remote control with it. I had been using a serial ir receiver but decided to try building my own USB receiver. This is based on the work by Dick Streefland found here: http://www.xs4all.nl/~dicks/avr/usbtiny/
USB IR Receiver – [Link]
Ian Johnston wasn’t content to use the usual RC control joystick for his RC flying. He decided to reinvent the controller using a couple of old PC joysticks, an Arduino and the Tx PCB from Thomas Scherrer’s LRS kit.
RC joystick transmitter using Arduino – [Link]
Here is my home-made kit of ATmega32 microcontroller interfacing. The ATmega32 controller is rich with features like onboard 32kB in-System programmable flash, 1 KB EEPROM, 2KB SRAM, 10bit ADC (8 channel), SPI bus inteface, TWI (compatible with I2C bus) interface, an USART, analog comparator, etc. That’s why I’ve selected it to load my kit with all those features.
Make-Yourself ATmega32 Starter’s Kit with LCD, I2C, SPI, RTC, ADC interfaces – [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]
Here is an easy an popular way to start using USB in your designs without going into learning the complicated USB protocol. This circuit converts normal USART signals from any microcontroller into USB compatible signals which can be directly connected to the PC. If u r designing a circuit and u need pc interface, then this is the best way, use USB, as the RS232 ports are disappearing from PCs and laptops very fast.
USART-to-USB converter using FT232BM chip – [Link]