Portable Digital Compass

Difficulty

Test & Tools

Summary

Not just a great project for the coming holiday break, this compass can be used to find your way home. The addition of a functional USB output will ensure if you're still lost, you can always charge your phone and call for help.

Materials Required

1	Arduino Compatible Monochrome OLED Display Module	XC4384
1	Arduino Compatible Nano Board	XC4414
1	Arduino Compatible 3 Axis Compass Magnetometer Module	XC4496
1	150mm Socket to Socket Jumper Leads - 40 Piece	WC6026
1	7805 +5V 1A Voltage Regulator TO-220 case	ZV1505
1	Battery Bank 4 x AA USB A SKT with Switch Black	MP3083
1	14500 Rechargeable Li-Ion Battery 800mAh 3.7V Nipple	SB2300

Resources

Download Project Resources

Table of Contents

Software and Libraries
Assembly
Programming
Use

Software and Libraries

Library	Author	Version
Adafruit_GFX	Adafruit	1.0.2
Adafruit_SSD1306	Adafruit	1.1.2
I2C-Sensor_Lib	Ingmar Splitt	0.8.2

Connection table

Nano	Compass Module	OLED Screen
3v3	VCC	VCC
A4	SDA	SDA
A5	SCL	SCL
GND	GND	GND

Assembly

Programming

//32 x 32 is what we'd use for the rotating compass
//draw a circle starting at 16,16    and with a radius of 16 (32 dia.)
int Cx = 16;
int Cy = 16;
screen.drawCircle(Cx,Cy, circle_radius, WHITE);
//center of the circle is at 16,16

int ax = sin(rad)   * circle_radius;
int ay = cos(rad)  * circle_radius;
int bx = sin(rad+half_pi)   * half_radius;
int by = cos(rad+half_pi)  * half_radius;
int cx = sin(rad-half_pi)    * half_radius;
int cy = cos(rad-half_pi)   * half_radius;

//north facing triangle is filled in
screen.fillTriangle(
        Cx + ax, Cy + ay,
        Cx + bx, Cy + by,
        Cx + cx, Cy + cy, WHITE);
screen.drawTriangle(
        Cx - ax, Cy - ay,       //reverse the outlined
        Cx + bx, Cy + by,
        Cx + cx, Cy + cy, WHITE);