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         rangeTimeout(), 
00035         rangingBusy(false) {
00036 
00037 }
00038 
00039 /*
00040  * Function:    startRanging
00041  * Args:        void
00042  * Returns:     void
00043  * Description: Sends command to module to start ranging.
00044  */
00045 void SRF08::startRanging() {
00046     //Create a two byte command. The first first byte is the register address
00047     // on the SRF08 to write to. The second byte is the command which is written
00048     // to that address ("Start ranging in cm" in this case).
00049     const char command[] = {0x00, 0x51};
00050     i2cMod.write(i2cAddress, command, 2);
00051     this->rangingBusy = true;
00052     rangeTimeout.attach(this, &SRF08::setRangingFinished, 0.07);
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() ) wait(0.01);   //Wait until ranging is finished
00074     const char command[]  = {0x02};           //Address of range register
00075     char response[] = {0x00, 0x00};
00076     i2cMod.write(i2cAddress, command, 1, 1);  //Send command
00077     i2cMod.read(i2cAddress, response, 2);     //Read 16bits result
00078     int range = (response[0]<<8)+response[1]; //Shift two bytes into int
00079     return range;                             //Return int range
00080 }
00081 
00082 /*
00083  * Function:    readLightIntensity
00084  * Args:        void
00085  * Returns:     int lightIntensity
00086  * Description: Reads the lightIntensity from the module
00087  *              The light intensity is updated if a range command is sent, so don't use
00088  *              this function only
00089  */
00090 int SRF08::getLightIntensity() {
00091     const char command[] = {0x01};           //Light intensity register
00092     char response[] = {0x00};
00093     i2cMod.write(i2cAddress, command, 1, 1); //Send command
00094     i2cMod.read(i2cAddress, response, 1);    //Read response
00095     int lightIntensity = response[0];
00096     return lightIntensity;
00097 }
00098 
00099 /*
00100  * Function:    setRangeRegister
00101  * Args:        rangeVal
00102  * Returns:     void
00103  * Description: Sets the maximum range for which the module waits for an echo
00104  *              The range is ((rangeVal x 43mm) + 43mm)
00105  *              The max range is about six meters
00106  */
00107 void SRF08::setRangeRegister(unsigned char rangeVal) {
00108     while (!rangingFinished() ) wait(0.01);  //Wait until ranging is finished
00109     char command[] = {0x02, rangeVal};       //Range register
00110     i2cMod.write(i2cAddress, command, 2);    //Send command
00111 }
00112 
00113 
00114 //Function setMaxGainRegister
00115 void SRF08::setMaxGainRegister(unsigned char gainVal) {
00116     while (!rangingFinished() ) wait(0.01);  //Wait until ranging is finished
00117     char command[] = {0x01, gainVal};        //Max gain register
00118     i2cMod.write(i2cAddress, command, 2);    //Send command
00119 }
00120 
00121 /*
00122  * Function:    setAddress
00123  * Args:        address
00124  * Returns:     void
00125  * Description: Sets the address of the module on the I2C bus. The factory default address is 0x0E (224)
00126  *                  The address can have the following values:
00127  *                      E0 | E2 | E4 | E6 ... FC | FE
00128  */
00129 void SRF08::setAddress(int address) {
00130     //Send address change sequence
00131     char command[] = {0x00, 0xA0};
00132     i2cMod.write(i2cAddress, command, 2);
00133     command[1] = 0xAA;
00134     i2cMod.write(i2cAddress, command, 2);
00135     command[1] = 0xA5;
00136     i2cMod.write(i2cAddress, command, 2);
00137     command[1] = address;
00138     i2cMod.write(i2cAddress, command, 2);
00139     //Save the updated address
00140     i2cAddress = address;
00141 }
00142 
00143 //Small helper function for Timeout object
00144 void SRF08::setRangingFinished() {
00145     this->rangingBusy = false;
00146 }