How to find your car in a parking lot

The easiest way it to use smart phone with GPS locator. When you park, simply record your location and when you need to find it use navigator which guides you to its place. If you don’t have such phone and want to build one, follow msuzuki777 instructable where he builds car tracker.

car_tracker

Device is pretty simple when building using modules. So here he uses Ublox NEO-6M GPS module, LSM303DLHC magnetometer, custom Arduino, Nokia 5110 LCD and Lithium battery. This locator simply remembers coordinates where your car is parked. When you need to find simply turn on and you will see how far you car is and what direction you need to go thanks to magnetic sensor based compass. You can find more uses of this devise. For instance when hiking – you can remember start location and let it guide you home when done.

Experimenting with Arduino based low speed BLDC control

Common hobby BLDC motors are meant to run on relatively high speeds. Take any plane, quadcopter or boat – low speeds aren’t required here. For high speed rotations BLDC drivers rely on back-EMF (or Hall-sensor) to sense rotation speed. Berryjam decided to see how slow he can run those motors with Arduino and triple half bridge chip – L6234.

Since standard speed controllers use square wave signals to drive the coils that aren’t noticeable in high speeds (maybe too noisy), in slow speed rotations steps become choppy. So here he used sine wave shaped current modulated by Arduino PWM. There are two options – using sine wave PWM or Space-Vector-PWM (SVPWM) – they both work well. Tests show that with standard BLDC motor he was able to get 2160 steps per revolution, or 0.16 degree precision which can be made even higher. It is hard to tell from video, but it seems that BLDC motor doesn’t seem to be good choice for stepping applications, since it is not designed to step and hold. Maybe it would find its place where very slow and accurate driving is required.

Driving SSD1306 based OLED display with DMA library

People love using OLED displays in their projects because they offer better contrast, color depth and different feel from LCD. So there are plenty of OLED display modules ready to be used with microcontroller boards like Arduino. Adafruit also offers great 128×64 SSD1306 based OLED display which has great library for Arduino. But problem is that there are so many Arduino variations with different processor families that using one generic library doesn’t ensure its efficiency. So the guys from grav-corp decided to tweak the library so it would work with Arduino Due much faster because of DMA.

SSD1306_driving_with_DMA

Arduino Due is equipped with ARM microcontroller which most of the features aren’t used by standard Arduino library that are initially built for AVR micros. And so the LCD is driven with SPI interface which works well with DMA. With standard library calls to display() function took about 2ms, with new implementation speed quadrupled and speed could be increased even more by rising SPI clock speed. But another main advantage is that using DAM practically frees CPU from writing data to LCD. Once set, DAM controller can write whole image stored in SD card while CPU can perform other tasks.

Arduino based laser pointer to honor Galileo

K.Crankshaw with his partners wanted to build something in Galileo’s memory who made important discoveries in astronomy. They though that the easiest way to learn sky objects is when someone or something points them. So they came up with Arduino based accurate laser pointer which can points its beam directly to wanted objects. Sounds cool.

arduino_galileo_pointer

They build built a wooden pan and tilt stepper motor driven mechanism which can point laser to any direction on a top half of sphere of sky. Arduino communicates to python code via serial interface to get desired sky object location then it drives motors to point its position with laser. Why not to scale it up to work with telescope?