CMPS03.cpp

00001 /**
00002  * @author Aaron Berk
00003  * 
00004  * @section LICENSE
00005  *
00006  * Copyright (c) 2010 ARM Limited
00007  *
00008  * Permission is hereby granted, free of charge, to any person obtaining a copy
00009  * of this software and associated documentation files (the "Software"), to deal
00010  * in the Software without restriction, including without limitation the rights
00011  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
00012  * copies of the Software, and to permit persons to whom the Software is
00013  * furnished to do so, subject to the following conditions:
00014  *
00015  * The above copyright notice and this permission notice shall be included in
00016  * all copies or substantial portions of the Software.
00017  *
00018  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
00019  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
00020  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
00021  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
00022  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
00023  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
00024  * THE SOFTWARE.
00025  *
00026  * @section DESCRIPTION
00027  *
00028  * CMPS03 digital compass module.
00029  *
00030  * Datasheet:
00031  *
00032  * http://www.robot-electronics.co.uk/htm/cmps3tech.htm
00033  */
00034 
00035 /**
00036  * Includes
00037  */
00038 #include "CMPS03.h"
00039 
00040 CMPS03::CMPS03(PinName sda, PinName scl, int address) {
00041 
00042     i2c = new I2C(sda, scl);
00043     //Compass designed to work at 100KHz. See datasheet for details.
00044     i2c->frequency(100000);
00045     i2cAddress = address;
00046 
00047 }
00048 
00049 char CMPS03::readSoftwareRevision(void){
00050 
00051     char registerNumber   = SOFTWARE_REVISION_REG;
00052     char registerContents = 0;
00053 
00054     //First, send the number of register we wish to read,
00055     //in this case, command register, number 0.
00056     i2c->write(i2cAddress, &registerNumber, 1);
00057     
00058     //Now, read one byte, which will be the contents of the command register.
00059     i2c->read(i2cAddress, &registerContents, 1);
00060     
00061     return registerContents;
00062     
00063 }
00064 
00065 int CMPS03::readBearing(void){
00066 
00067     char registerNumber = COMPASS_BEARING_WORD_REG;
00068     char registerContents[2] = {0x00, 0x00};
00069     
00070     //First, send the number of register we wish to read,
00071     //in this case, register numbers 2, 3, which hold the
00072     //compass bearing as a 16-bit word.
00073     i2c->write(i2cAddress, &registerNumber, 1);
00074     
00075     //Now read two bytes which will be the contents of
00076     //these registers.
00077     i2c->read(i2cAddress, registerContents, 2);
00078     
00079     //Register 2 [read first], was the high byte, followed by
00080     //register 3 [read second], which was the low byte.
00081     int bearing = ((int)registerContents[0] << 8) | ((int)registerContents[1]);
00082     
00083     return bearing;
00084     
00085 }