Arduino Uno uses another Atmega8U2 microcontroller to perform USB interface. But having microcontroller instead FT232 chips this gives more power to do interesting things. Michael updated Atmega8U2 firmware using DFU protocol that allows to flash USB devices differently. By flashing different firmware like LUFA you can turn Arduino in to generic USB device.

As demonstration Michael have flashed generic USB HID keyboard firmware. Having three push buttons attached to Arduino board, he was able to do various tasks like volume control, key press like you would do with normal PC keyboard. Why not making large copy and paste buttons hard glued to your desk…

1-wire devices are common among hobbyists. This is because of accuracy, simple interface and popularity. One problem is that microcontrollers don’t have some sort of 1-wire interface that can be used out of the box like I2C or SPI. Anyway using 1-wire isn’t that hard as it may look like. To break this barrier Karve have wrote detailed tutorial on interfacing popular DS18B20 temperature sensor to TI Launchpad MSP-EXP430G2.

He analyzed every step that needs to be done in order to initialize 1-wire. All examples are followed with oscilloscope captured waveforms. Using bit-banging on microcontroller pins finally he red 12 bit temperature value which then was converted to get human readable value. So this is great read to refresh some skills and maybe do something interesting with 1-wire devices.

If you are using computer PSU as bench power supply you probably know this annoying feature when safety triggers and the only way to reset supply is to reattach green wire to ground. Safety is safety but what about convenience. Simple switch might work fine but Henry wanted more intelligent approach to solution.

So he used an Attiny85 microcontroller to take care of this. Simple circuit has a button input, status LED. As input it takes voltage from 5V red wire of PSU. Microcontroller is powered from purple wire of PSU which stays 5V when safety is triggered. And finally green wire is attached to MCU so it could control according to algorithm. Having microcontroller power he added several features selectable with single button. PSU can be turned on and off with simple press. If button is pressed and hold for loner time PSU safety features are overridden for mad scientist projects (beware of danger). Project code is written in Arduino style using MITs guide on putting Arduino in to Tiny MCU.

Vinod recently shared his latest project where he built a video player combining AVR Atemga32 microcontroller, SD card and Nokia 6030 LCD. As he describes process evolved step by step. Firs of all the idea was to display images on LCD. Then with SD storage he was able to display image slideshows with 1s timer. Then naturally this project evolved in to video player by implementing slideshow at high frame rate.

His research begins with problem how to convert video to frame pictures. For this a ffpmeg Linux program suited which converts video in to frames. Then python script extracts pixel data that can be stored in to SD memory. After videos are done, next logical step is audio. He was able to extract audio in to wav which is easy to play with microcontroller using PWM. Last headache was to synchronize audio with video. Vinod did some math and found audio/video sample mixing ratio. Simple error correction keeps them synchronized. And finally it plays video at 9 fps at 132×65 resolution and audio at 11000 b/s rate. MCU program and python script are available in case you will want to give a try.