Brent Dekker / SRF08

Library for interfacing the SRF08 ultrasonic range sensor. Most functions of the SRF08 are covered, including interrupt-based waiting for the ranging process to finish

Dependents:   DISCO-F746NG_LCDTS_demo Srf08Test

/media/uploads/brentdekker/ultrasonic-range-finder-srf08.jpg

SRF08

Warning

Don't forget to add the pullup resistors from 5v to SDA and SCL!

Information on the SRF08 can be found here: http://www.robot-electronics.co.uk/htm/srf08tech.shtml

Example program

#include "mbed.h"
#include "SRF08.h"

Serial PC(USBTX, USBRX);       //Debug port to PC
SRF08 rangeMod1(p28, p27, 0xE4); //SRF08 ranging module 1
SRF08 rangeMod2(p28, p27, 0xE2); //SRF08 ranging module 2

int main() {
    PC.printf("Start ranging test \n");
    rangeMod1.setAddress(0xE4); //Factory default is 0xE0
    while(1) {
        rangeMod1.startRanging();
        while (!rangeMod1.rangingFinished() ) wait(0.01);
        int range1 = rangeMod1.getRange();
        int light1 = rangeMod1.getLightIntensity();
        rangeMod2.startRanging();
        while (!rangeMod2.rangingFinished() ) wait(0.01);
        int range2 = rangeMod2.getRange();
        PC.printf(" Range_1: %i", range1);
        PC.printf(" Range_2: %i", range2);
        PC.printf(" Light_1: %i", light1);
        PC.printf("\n");
    }
}

Library

Import library
SRF08 - SRF08 Class Reference

Public Member Functions

SRF08 (PinName SDA, PinName SCL, int i2cAddress)
Create a SRF08 object connected to the specified I2C pins and address.
void startRanging ()
Send the "Start ranging in cm" command via I2C.
bool rangingFinished ()
Checks if the module has finished ranging.
int getRange ()
Gets the measured range from the module.
int getLightIntensity ()
Gets the measured light intensity from the module.
void setRangeRegister (unsigned char rangeVal)
Sets the range register of the SRF08 for faster ranging.
void setMaxGainRegister (unsigned char gainVal)
Sets the max gain register of the SRF08 .
void setAddress (int i2cAddress)
Changes the I2C address of the SRF08 .

SRF08.h@1:76fb116fa28d, 2012-07-10 (annotated)

Committer:
brentdekker
Date:
Tue Jul 10 08:48:02 2012 +0000
Revision:
1:76fb116fa28d
Parent:
0:4e0a8193b92e
Child:
2:ca82f89f415d
Extra functions added for more optimal processor-time use

Who changed what in which revision?

UserRevisionLine numberNew contents of line
brentdekker 0:4e0a8193b92e 1
brentdekker 0:4e0a8193b92e 2 /*
brentdekker 0:4e0a8193b92e 3 Copyright (c) 2010 Chris Styles (chris dot styles at mbed dot org)
brentdekker 0:4e0a8193b92e 4
brentdekker 0:4e0a8193b92e 5 Permission is hereby granted, free of charge, to any person obtaining a copy
brentdekker 0:4e0a8193b92e 6 of this software and associated documentation files (the "Software"), to deal
brentdekker 0:4e0a8193b92e 7 in the Software without restriction, including without limitation the rights
brentdekker 0:4e0a8193b92e 8 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
brentdekker 0:4e0a8193b92e 9 copies of the Software, and to permit persons to whom the Software is
brentdekker 0:4e0a8193b92e 10 furnished to do so, subject to the following conditions:
brentdekker 0:4e0a8193b92e 11
brentdekker 0:4e0a8193b92e 12 The above copyright notice and this permission notice shall be included in
brentdekker 0:4e0a8193b92e 13 all copies or substantial portions of the Software.
brentdekker 0:4e0a8193b92e 14
brentdekker 0:4e0a8193b92e 15 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
brentdekker 0:4e0a8193b92e 16 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
brentdekker 0:4e0a8193b92e 17 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
brentdekker 0:4e0a8193b92e 18 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
brentdekker 0:4e0a8193b92e 19 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
brentdekker 0:4e0a8193b92e 20 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
brentdekker 0:4e0a8193b92e 21 THE SOFTWARE.
brentdekker 0:4e0a8193b92e 22 */
brentdekker 0:4e0a8193b92e 23
brentdekker 0:4e0a8193b92e 24 #ifndef SRF08_H
brentdekker 0:4e0a8193b92e 25 #define SRF08_H
brentdekker 0:4e0a8193b92e 26
brentdekker 0:4e0a8193b92e 27 #include "mbed.h"
brentdekker 0:4e0a8193b92e 28
brentdekker 1:76fb116fa28d 29 #define RANGEBUFSIZE 5
brentdekker 1:76fb116fa28d 30
brentdekker 0:4e0a8193b92e 31 /*
brentdekker 0:4e0a8193b92e 32 * The SRF08 is an Ultrasonic range finder, with an I2C interface that allows the measurement to be read directly in centimetres
brentdekker 0:4e0a8193b92e 33 */
brentdekker 0:4e0a8193b92e 34 class SRF08 {
brentdekker 0:4e0a8193b92e 35
brentdekker 0:4e0a8193b92e 36 public:
brentdekker 0:4e0a8193b92e 37
brentdekker 0:4e0a8193b92e 38 /*
brentdekker 0:4e0a8193b92e 39 * Constructor: SRF08
brentdekker 0:4e0a8193b92e 40 * Args: PinName sda: Data pin of I2C bus to which module is connected
brentdekker 0:4e0a8193b92e 41 * PinName scl: Clock pin of I2C bus to which module is connected
brentdekker 0:4e0a8193b92e 42 * int addr: address of module on the I2C bus
brentdekker 0:4e0a8193b92e 43 * Returns: void
brentdekker 0:4e0a8193b92e 44 * Description: Creates an instance of the SRF08 to communicate with a sRF08 module
brentdekker 0:4e0a8193b92e 45 */
brentdekker 0:4e0a8193b92e 46 SRF08(PinName sda, PinName scl, int addr);
brentdekker 0:4e0a8193b92e 47
brentdekker 0:4e0a8193b92e 48 /*
brentdekker 0:4e0a8193b92e 49 * Destructor: ~SRF08
brentdekker 0:4e0a8193b92e 50 * Args: void
brentdekker 0:4e0a8193b92e 51 * Returns: void
brentdekker 0:4e0a8193b92e 52 * Description: Destroys instance of SRF08 class
brentdekker 0:4e0a8193b92e 53 */
brentdekker 0:4e0a8193b92e 54 ~SRF08();
brentdekker 1:76fb116fa28d 55
brentdekker 1:76fb116fa28d 56 /*
brentdekker 1:76fb116fa28d 57 * Function: startRanging
brentdekker 1:76fb116fa28d 58 * Args: void
brentdekker 1:76fb116fa28d 59 * Returns: void
brentdekker 1:76fb116fa28d 60 * Description: Sends command to module to start ranging.
brentdekker 1:76fb116fa28d 61 */
brentdekker 1:76fb116fa28d 62 void startRanging();
brentdekker 1:76fb116fa28d 63
brentdekker 1:76fb116fa28d 64 /*
brentdekker 1:76fb116fa28d 65 * Function: rangingFinished
brentdekker 1:76fb116fa28d 66 * Args: void
brentdekker 1:76fb116fa28d 67 * Returns: Bool: whether ranging is finished
brentdekker 1:76fb116fa28d 68 * Description: Checks if the ranging process on the module is finished
brentdekker 1:76fb116fa28d 69 */
brentdekker 1:76fb116fa28d 70 bool rangingFinished();
brentdekker 1:76fb116fa28d 71
brentdekker 1:76fb116fa28d 72 /*
brentdekker 1:76fb116fa28d 73 * Function: getRange
brentdekker 1:76fb116fa28d 74 * Args: void
brentdekker 1:76fb116fa28d 75 * Returns: int range
brentdekker 1:76fb116fa28d 76 * Description: Range in cm. This function should only be called when ranging is finished, otherwise previous value is returned
brentdekker 1:76fb116fa28d 77 */
brentdekker 1:76fb116fa28d 78 void getRange();
brentdekker 1:76fb116fa28d 79
brentdekker 0:4e0a8193b92e 80 /*
brentdekker 0:4e0a8193b92e 81 * Function: readRange
brentdekker 0:4e0a8193b92e 82 * Args: void
brentdekker 0:4e0a8193b92e 83 * Returns: int range
brentdekker 0:4e0a8193b92e 84 * Description: Reads the range register and converts it to a usable value
brentdekker 0:4e0a8193b92e 85 */
brentdekker 1:76fb116fa28d 86 int readRange();
brentdekker 1:76fb116fa28d 87
brentdekker 1:76fb116fa28d 88 /*
brentdekker 1:76fb116fa28d 89 * Function: readBufRange
brentdekker 1:76fb116fa28d 90 * Args: void
brentdekker 1:76fb116fa28d 91 * Returns: int range
brentdekker 1:76fb116fa28d 92 * Description: Reads the range register, adds it to an array and converts it to a filtered value
brentdekker 1:76fb116fa28d 93 */
brentdekker 1:76fb116fa28d 94 //int readBufRange();
brentdekker 0:4e0a8193b92e 95
brentdekker 0:4e0a8193b92e 96 /*
brentdekker 0:4e0a8193b92e 97 * Function: readLightIntensity
brentdekker 0:4e0a8193b92e 98 * Args: void
brentdekker 0:4e0a8193b92e 99 * Returns: int lightIntensity
brentdekker 0:4e0a8193b92e 100 * Description: Reads the lightIntensity from the module
brentdekker 0:4e0a8193b92e 101 */
brentdekker 0:4e0a8193b92e 102 int readLightIntensity();
brentdekker 0:4e0a8193b92e 103
brentdekker 0:4e0a8193b92e 104 /*
brentdekker 0:4e0a8193b92e 105 * Function: setRangeRegister
brentdekker 0:4e0a8193b92e 106 * Args: rangeVal
brentdekker 0:4e0a8193b92e 107 * Returns: void
brentdekker 0:4e0a8193b92e 108 * Description: Sets the maximum range for which the module waits for an echo
brentdekker 0:4e0a8193b92e 109 * The range is ((rangeVal x 43mm) + 43mm)
brentdekker 0:4e0a8193b92e 110 * The max range is about six meters
brentdekker 0:4e0a8193b92e 111 */
brentdekker 0:4e0a8193b92e 112 void setRangeRegister(char rangeVal);
brentdekker 0:4e0a8193b92e 113
brentdekker 0:4e0a8193b92e 114 /*
brentdekker 0:4e0a8193b92e 115 * Function: setAddress
brentdekker 0:4e0a8193b92e 116 * Args: address
brentdekker 0:4e0a8193b92e 117 * Returns: void
brentdekker 0:4e0a8193b92e 118 * Description: Sets the address of the module on the I2C bus. The factory default address is 0x0E (224)
brentdekker 0:4e0a8193b92e 119 * The address can have the following values:
brentdekker 0:4e0a8193b92e 120 * E0 | E2 | E4 | E6 ... FC | FE
brentdekker 0:4e0a8193b92e 121 */
brentdekker 0:4e0a8193b92e 122 void setAddress(char address);
brentdekker 0:4e0a8193b92e 123
brentdekker 0:4e0a8193b92e 124 private:
brentdekker 0:4e0a8193b92e 125 I2C m_i2c;
brentdekker 0:4e0a8193b92e 126 int m_addr;
brentdekker 1:76fb116fa28d 127 int rangeBuf[RANGEBUFSIZE];
brentdekker 1:76fb116fa28d 128 int rangeBufIndex;
brentdekker 1:76fb116fa28d 129
brentdekker 1:76fb116fa28d 130 int getAverageBufRange(void);
brentdekker 0:4e0a8193b92e 131 };
brentdekker 0:4e0a8193b92e 132
brentdekker 0:4e0a8193b92e 133 #endif