Compass
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Breadboard with Compass module, ShiftBrite, Boarduino, calibration button with indicator, & FTDI serial out connected.
Components
- Compass Module CMPS03 http://www.robot-electronics.co.uk/htm/cmps3tech.htm
- DC Boarduino http://learn.adafruit.com/boarduino-kits/dc-parts-list
- FTDI Friend http://www.adafruit.com/products/284
- ShiftBrite http://macetech.com/blog/node/54
Other potential components
- SCF5740 Siemens (OSRAM) 4 digit display http://catalog.osram-os.com/media/_en/Graphics/00034126_0.pdf
- 0.96" OLED Display https://www.adafruit.com/products/684
- FTDI/USB http://www.parallax.com/catalog/integrated-circuits/ftdi
- RGB LED http://www.taydaelectronics.com/rgb-led-5mm.html
- RGBpixel
Future potential SMD components
Other products
Schematic
Indicates wiring for RGBpixel LEDs, as opposed to ShiftBrite
Code
The following will give a compass heading via serial monitor with the CMPS03
/* CMPS03 with arduino I2C example This will display a value of 0 - 359 for a full rotation of the compass. The SDA line is on analog pin 4 of the arduino and is connected to pin 3 of the CMPS03. The SCL line is on analog pin 5 of the arduino and is conected to pin 2 of the CMPS03. Both SDA and SCL are also connected to the +5v via a couple of 1k8 resistors. A switch to callibrate the CMPS03 can be connected between pin 6 of the CMPS03 and the ground. */ #include <Wire.h> #define ADDRESS 0x60 //defines address of compass void setup(){ Wire.begin(); //conects I2C Serial.begin(9600); } void loop(){ byte highByte; byte lowByte; Wire.beginTransmission(ADDRESS); //starts communication with cmps03 Wire.write(2); //Sends the register we wish to read Wire.endTransmission(); Wire.requestFrom(ADDRESS, 2); //requests high byte while(Wire.available() < 2); //while there is a byte to receive highByte = Wire.read(); //reads the byte as an integer lowByte = Wire.read(); int bearing = ((highByte<<8)+lowByte)/10; Serial.println(bearing); delay(100); }
This code will provide x/y magnetic strength and computed angle with the HM55B
/* ///////////////////////////////// Htachi HM55B Compass parallax (#) AUTHOR: kiilo kiilo@kiilo.org License: http://creativecommons.org/licenses/by-nc-sa/2.5/ch/ http://parallax.com/Store/Microcontrollers/BASICStampModules/tabid/134/txtSearch/hm55b/List/1/ProductID/98/Default.aspx?SortField=ProductName%2cProductName http://sage.medienkunst.ch/tiki-index.php?page=HowTo_Arduino_Parallax_HM55B_Kompass http://playground.arduino.cc/HM55B ///////////////////////////////// */ #include <math.h> // (no semicolon) //// VARS byte CLK_pin = 8; byte EN_pin = 9; byte DIO_pin = 10; int X_Data = 0; int Y_Data = 0; int angle; //// FUNCTIONS void ShiftOut(int Value, int BitsCount) { for(int i = BitsCount; i >= 0; i--) { digitalWrite(CLK_pin, LOW); if ((Value & 1 << i) == ( 1 << i)) { digitalWrite(DIO_pin, HIGH); //Serial.print("1"); } else { digitalWrite(DIO_pin, LOW); //Serial.print("0"); } digitalWrite(CLK_pin, HIGH); delayMicroseconds(1); } //Serial.print(" "); } int ShiftIn(int BitsCount) { int ShiftIn_result; ShiftIn_result = 0; pinMode(DIO_pin, INPUT); for(int i = BitsCount; i >= 0; i--) { digitalWrite(CLK_pin, HIGH); delayMicroseconds(1); if (digitalRead(DIO_pin) == HIGH) { ShiftIn_result = (ShiftIn_result << 1) + 1; //Serial.print("x"); } else { ShiftIn_result = (ShiftIn_result << 1) + 0; //Serial.print("_"); } digitalWrite(CLK_pin, LOW); delayMicroseconds(1); } //Serial.print(":"); // below is difficult to understand: // if bit 11 is Set the value is negative // the representation of negative values you // have to add B11111000 in the upper Byte of // the integer. // see: http://en.wikipedia.org/wiki/Two%27s_complement if ((ShiftIn_result & 1 << 11) == 1 << 11) { ShiftIn_result = (B11111000 << 8) | ShiftIn_result; } return ShiftIn_result; } void HM55B_Reset() { pinMode(DIO_pin, OUTPUT); digitalWrite(EN_pin, LOW); ShiftOut(B0000, 3); digitalWrite(EN_pin, HIGH); } void HM55B_StartMeasurementCommand() { pinMode(DIO_pin, OUTPUT); digitalWrite(EN_pin, LOW); ShiftOut(B1000, 3); digitalWrite(EN_pin, HIGH); } int HM55B_ReadCommand() { int result = 0; pinMode(DIO_pin, OUTPUT); digitalWrite(EN_pin, LOW); ShiftOut(B1100, 3); result = ShiftIn(3); return result; } void setup() { Serial.begin(9600); pinMode(EN_pin, OUTPUT); pinMode(CLK_pin, OUTPUT); pinMode(DIO_pin, INPUT); HM55B_Reset(); } void loop() { HM55B_StartMeasurementCommand(); // necessary!! delay(40); // the data is 40ms later ready Serial.print(HM55B_ReadCommand()); // read data and print Status Serial.print(" "); X_Data = ShiftIn(11); // Field strength in X Y_Data = ShiftIn(11); // and Y direction Serial.print(X_Data); // print X strength Serial.print(" "); Serial.print(Y_Data); // print Y strength Serial.print(" "); digitalWrite(EN_pin, HIGH); // ok deselect chip angle = 180 * (atan2(-1 * Y_Data , X_Data) / M_PI); // angle is atan( -y/x) !!! Serial.print(angle); // print angle Serial.println(""); }
See also: Compass_Vibro_Anklet