It’s taken awhile to get to this point, finally have the project to a good enough point to show off what this headlight looks like!
Revolights, A revolution in bicycle lighting, now have light projected exactly where it is needed to see obstacles in front, while maintaining 360 degree visibility. Wheel mounted lighting capable of projecting forwards and backwards.
Mounted to each wheel are a pair of rings that have equally spaced LEDs. The rings calculate how fast the bike is moving and only turn the LEDs on in the front or in the rear of the bike while moving. Picture shows the wheels spinning, and the lighting effect. Stay tuned for more info! (patent pending)
Meticilous breakout of accelerometer to breadboard
There are a few libraries out there for doing I²C (I2C) using the USI or TWI hardware for AVRs. Unfortunately documentation that explains exactly what is happening is hard to come by. There are a number of well done explanations on what it is, and extensive examples for PICs, though few for AVRs and much less for ATTiny45s.
So I decided to do a simple bit-banged version for my own project. Click one of the links for the full article.
Here is a link to an excellent explanation of I2C and it’s general protocol (no need to re-explain it). It sounds rather simple to implement, though the method and code to make it work on AVR is a little counter intuitive.
Through a group organized at Stanford’s Engineers for a Sustainable World (EWB) chapter our team just finished the first version of a solar powered freezer for the developing world that uses no electricity.
The system works through the Carbon-Methanol adsorption cycle, which uses sunlight during the day and low temperatures during the night. We have taken some great lengths to document the whole procedure, and I have just recently posted a few blog entries on the Stanford Appropriate Technology website we set up. Check it out.
Yesterday we had our robot competition for ME 218B – Mechatronics. The robot built by my team and I, powerfully named Robbie O’Doyle performed pretty well… Due to a problem with the tape on the playing field, he hit 4 targets with his nerf ball projectiles then got lost. But we were damn proud.
Documenting the first successful test using the idea of persistence of vision and my own LED circuit. Shown below is an ATMega8 microcontroller connected to 8 LEDs through 8-100 Ohm resistors. Flickering the LEDs in a certain order at a certain rate while being moved creates the illusion of text being written.
Circuit v1.0 of the LED POV text writer. ATMega8 chip on the right with the 2×6 pin programming header connected.
Circuit v1.0 exposure photo while moving, displaying 3-2-1
Here is the second iteration of the circuit design for running the 8×8 LED Matrix. This time I attempted to lower the number of signal lines being run out of the ATMega1280 microcontroller by using 2x 74HC595 Shift Registers. Doing this reduced the number of signal lines from 16 to 3, a huge drop, with no noticeable loss of performance.
This circuit is only running the green LEDs in the display however.