Attiny85 based POV display

POV (Persistence Of Vision) displays can be great way of displaying more information with small number of indicators. For instance you can display words and graphics with like 5 LEDs. The only condition here is that things have to move mechanically. In other hand POV display can be really fun to make. If you look around the internet, you will find quite complex ones including 3D. This one is pretty simple and can be fir in to $5 budget. All it needs a DC motor, Attiny85 and 96 LEDs. LEDs are mounted on cardboard with hot glue. They are connected to small custom Attiny85 board directly with wires. Microcontroller is powered with coin cell battery which is enough to run program and light the LEDs. It seems that there is no synchronization between motor spins and character display, so frame rate is determined by using trial and error method. Since different DC motors have different characteristics, you may need to tweak timer values to get desired results. Continue reading

ATmega88 based POV weather station generates its own power

We like POV(Persistence of Vision) projects – specially those with unique ways to transmit energy to the turning row of LEDs (Light Emitting Diodes). This POV however beats the rest that we have seen so far – this one is a freakin weather station. Instead of displaying graphics this POV displays the current temperature and relative humidity. And the best thing we like about this guy? It generates its own energy! It uses a stepper motor as a generator, when a stepper motor is turned current flow through its wires. It is then rectified using a set of diodes and stored into a 6 – capacitor charge bank. The Charged stored in the bank is then fed to a  TPS5420 buck converter that outputs 3.5V – just enough to drive the ATmega88 microcontroller and the 8 – LED array. The ATmega88 is operating at 10MHz while it gathers humidity and temperature data from an SHT21 using I2C protocol. To sync when to start displaying, it uses a hall effect sensor from an old floppy drive  – this is used to determine absolute… Continue reading

Watch Out, this Bicycle Can Speak!

Well, for those of you that have an exercise bicycle in your home, you must be quite familiar with the odometer that sticks on the exercise bicycle. Have you ever thought to modify the odometer into a more powerful reading tool? If you did, then today is your lucky day… Ladies and gentlemen, let’s meet this incredible “Spoke-o-dometer,” where it’s actually a more advanced device than Cyclocomputer, which is a device mounted on a bicycle that calculates and displays trip information. The biggest different of the Spoke-o-dometer and the ordinary cyclocomputer is the latter always being attached to the handlebar for easy viewing, while the Spoke-o-dometer is displays on the bicycle’s wheels! Technically, this Spoke-o-dometer involves creating a Persistance of Vision (POV) device for mounting on a bike wheel. Although there are a few of these devices already on the market, this project is differs in that it combines a basic bike meter with the POV readout. Furthermore, the device will display speed and total distance traveled, soon after you rid on the bicycle! Unlike those standard bike computers, this… Continue reading