micro:bit Projects: North Pointer (3 Bit Tilt Compensated e-Compass) @microbit_edu #microbit #microbitlove #microbitmonday
From Shahariar via hackster.io
The front of micro:bit has 5X5 LED matrix display, good enough for scrolling text, animation, etc. There is a magnetometer on the back. As for my first project, I wanted to see, if I can make an accurate compass. To my utter surprise, the the compass heading is pretty accurate in degrees. But displaying the heading is annoying because it scrolls, so a pointer like compass with 3 LEDs forming a Line pointer pointing north.
A compass has full 360 degrees, each degree can be divided into 60 minutes and further division is possible. This compass has 8 positions only with 45 degrees of resolution, not very practical for navigation but you can roughly get an idea of direction.
Since, the compass works by measuring the earth’s magnetic field strength which depends on the location and the orientation of the sensor (or micro:bit board), it is necessary to calibrate the compass by measuring minimum to maximum field strength range and the board tilt using accelerometer to perform critical trigonometric mathematics.
That’s why, after flashing the code for the first time, a calibration test needs to be performed. On the first run after flashing, a message will appear and user will be asked to draw a circle with LEDs on the 5X5 matrix display by tilting the board in different direction. Once done, the compass pointer will appear and point appropriately.
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