2015 hdd motor clock using POV and BLDC v2

Рет қаралды 27,354

9 жыл бұрын

This is my little project: clock made of old broken hard disk.
This is an updated version of my previous movie on this subject
The project involves controlling HDD motor (3 wire brushless dc electric type BLDC) using open loop control without feedback, and using back electric motor force feedback to synchronize engine pulses with optimal point in time for them.
Digits are displayed by flashing 1W power LED-s behind rotating disc with painted digits. Each flash is circa 150 microseconds. Due to POV (persistence of vision) effect the digits look very stable for the user.
I am not using any special controller. Only Arduino, H-bridges for driving motor coils, and circuit for obtaining BEMF (back elecric motor force) from each coil and converting it to digital (high/low) signal to drive Arduino interrupt.
I have designed my own custom board which is a modified Arduino (something between UNO and PRO NANO) + added additional parts including real time clock. It is designed to fit on the back of a standard 3,5" HDD.
Software is very dependent on interrupts. I am using not only officially available interrupts (attachInterrupt) but also additional libraries to use all available timers and interrupts.

Пікірлер: 5

@damago1 8 жыл бұрын

I am using back electrict motor force detection. I have invented my own method of measuring BEMF using only one arduino pin. To position where is the 'zero' digit I am using photo interrupter (os25b10) - I am using it only once after start of the engine. You don't need it after the BEMF method stabilizes itself. In later design I am using cheap TCRT5000 - Infrared Reflective/Proximity Sensor which costs

@Tu1911 8 жыл бұрын

+damago1 Glad to see your reply, i was checking some propeller clock projects when i saw your project, i think your project is way much cooler(harder) than the normal propeller clock, good jobs

@Tu1911 8 жыл бұрын

one question, which method did you use to detect the hard disk position so u can flash the leds at the right moment

@damago1 7 жыл бұрын

I use two interrupts: one for BEMF (Atmega has a built in comparator able to fire interrupt), and another for timing the led on/off sequences. I know when I am switching the coils (BEMF interrupt), immediately after BEMF interrupt I am setting Atmega timer to X nanoseconds (usually 100-120ns), when this time elapses during timer interrupt I turn the LED on, set timer again to fire interrupt after another 50-150ns (depending on how dark/bright the digits should be) and when the interrupt fires again I turn the led off. And wait for another BEMF interrupt.