SRF08.cpp

00001 /*
00002 Copyright (c) 2012 Brent Dekker
00003  
00004 Permission is hereby granted, free of charge, to any person obtaining a copy
00005 of this software and associated documentation files (the "Software"), to deal
00006 in the Software without restriction, including without limitation the rights
00007 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
00008 copies of the Software, and to permit persons to whom the Software is
00009 furnished to do so, subject to the following conditions:
00010  
00011 The above copyright notice and this permission notice shall be included in
00012 all copies or substantial portions of the Software.
00013  
00014 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
00015 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
00016 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
00017 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
00018 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
00019 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
00020 THE SOFTWARE.
00021 */
00022  
00023 #include "SRF08.h"
00024  
00025 /*
00026  * Constructor: SRF08
00027  * Args:
00028  * Returns:     void
00029  * Description: Creates an instance of the SRF08 to communicate with a sRF08 module
00030  */
00031 SRF08::SRF08(PinName SDA, PinName SCL, int i2cAddress) :
00032         i2cMod(SDA, SCL), 
00033         i2cAddress(i2cAddress),  
00034         rangingBusy(false) {
00035  
00036 }
00037  
00038 /*
00039  * Function:    startRanging
00040  * Args:        void
00041  * Returns:     void
00042  * Description: Sends command to module to start ranging.
00043  */
00044 void SRF08::startRanging() {
00045     //Create a two byte command. The first first byte is the register address
00046     // on the SRF08 to write to. The second byte is the command which is written
00047     // to that address ("Start ranging in cm" in this case).
00048     const char command[] = {0x00, 0x51};
00049     i2cMod.write(i2cAddress, command, 2);
00050     this->rangingBusy = true;
00051     Thread::wait(70);
00052     setRangingFinished();
00053 }
00054  
00055 /*
00056  * Function:    rangingFinished
00057  * Args:        void
00058  * Returns:     Bool: whether ranging is finished
00059  * Description: Checks if the ranging process on the module is finished
00060  */
00061 bool SRF08::rangingFinished() {
00062     if(this->rangingBusy) return false;
00063     return true;
00064 }
00065  
00066 /*
00067  * Function:    getRange
00068  * Args:        void
00069  * Returns:     int range
00070  * Description: Range in cm. This function should only be called when ranging is finished, otherwise previous value is returned
00071  */
00072 int SRF08::getRange() {
00073     while (!rangingFinished() ) 
00074         Thread::wait(10);   //Wait until ranging is finished
00075     const char command[]  = {0x02};           //Address of range register
00076     char response[] = {0x00, 0x00};
00077     i2cMod.write(i2cAddress, command, 1, 1);  //Send command
00078     i2cMod.read(i2cAddress, response, 2);     //Read 16bits result
00079     int range = (response[0]<<8)+response[1]; //Shift two bytes into int
00080     return range;                             //Return int range
00081 }
00082  
00083 /*
00084  * Function:    readLightIntensity
00085  * Args:        void
00086  * Returns:     int lightIntensity
00087  * Description: Reads the lightIntensity from the module
00088  *              The light intensity is updated if a range command is sent, so don't use
00089  *              this function only
00090  */
00091 int SRF08::getLightIntensity() {
00092     const char command[] = {0x01};           //Light intensity register
00093     char response[] = {0x00};
00094     i2cMod.write(i2cAddress, command, 1, 1); //Send command
00095     i2cMod.read(i2cAddress, response, 1);    //Read response
00096     int lightIntensity = response[0];
00097     return lightIntensity;
00098 }
00099  
00100 /*
00101  * Function:    setRangeRegister
00102  * Args:        rangeVal
00103  * Returns:     void
00104  * Description: Sets the maximum range for which the module waits for an echo
00105  *              The range is ((rangeVal x 43mm) + 43mm)
00106  *              The max range is about six meters
00107  */
00108 void SRF08::setRangeRegister(unsigned char rangeVal) {
00109     while (!rangingFinished() ) 
00110         Thread::wait(10);                    //Wait until ranging is finished
00111     char command[] = {0x02, rangeVal};       //Range register
00112     i2cMod.write(i2cAddress, command, 2);    //Send command
00113 }
00114  
00115  
00116 //Function setMaxGainRegister
00117 void SRF08::setMaxGainRegister(unsigned char gainVal) {
00118     while (!rangingFinished() ) 
00119         Thread::wait(10);                    //Wait until ranging is finished
00120     char command[] = {0x01, gainVal};        //Max gain register
00121     i2cMod.write(i2cAddress, command, 2);    //Send command
00122 }
00123  
00124 /*
00125  * Function:    setAddress
00126  * Args:        address
00127  * Returns:     void
00128  * Description: Sets the address of the module on the I2C bus. The factory default address is 0x0E (224)
00129  *                  The address can have the following values:
00130  *                      E0 | E2 | E4 | E6 ... FC | FE
00131  */
00132 void SRF08::setAddress(int address) {
00133     //Send address change sequence
00134     char command[] = {0x00, 0xA0};
00135     i2cMod.write(i2cAddress, command, 2);
00136     command[1] = 0xAA;
00137     i2cMod.write(i2cAddress, command, 2);
00138     command[1] = 0xA5;
00139     i2cMod.write(i2cAddress, command, 2);
00140     command[1] = address;
00141     i2cMod.write(i2cAddress, command, 2);
00142     //Save the updated address
00143     i2cAddress = address;
00144 }
00145  
00146 //Small helper function for Timeout object
00147 void SRF08::setRangingFinished() {
00148     this->rangingBusy = false;
00149 }
00150