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
Fork of SRF08 by
SRF08.cpp
- Committer:
- brentdekker
- Date:
- 2012-07-05
- Revision:
- 0:4e0a8193b92e
- Child:
- 1:76fb116fa28d
File content as of revision 0:4e0a8193b92e:
/* Copyright (c) 2010 Chris Styles ( chris dot styles at mbed dot org ) Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ #include "SRF08.h" /* * Constructor: SRF08 * Args: PinName sda: Data pin of I2C bus to which module is connected * PinName scl: Clock pin of I2C bus to which module is connected * int addr: address of module on the I2C bus * Returns: void * Description: Creates an instance of the SRF08 to communicate with a sRF08 module */ SRF08::SRF08(PinName sda, PinName scl, int addr) : m_i2c(sda, scl), m_addr(addr) { char cmd[2]; // Set up SRF08 max range and receiver sensitivity over I2C bus cmd[0] = 0x02; // Range register cmd[1] = 0xFF; m_i2c.write(m_addr, cmd, 2); cmd[0] = 0x01; // Receiver gain register cmd[1] = 0x1F; // Set max receiver gain m_i2c.write(m_addr, cmd, 2); } /* * Destructor: ~SRF08 * Args: void * Returns: void * Description: Destroys instance of SRF08 class */ SRF08::~SRF08() { } /* * Function: readRange * Args: void * Returns: int range * Description: Reads the range register and converts it to a usable value */ int SRF08::read() { char cmd[2]; char echo[2]; // Get range data from SRF08 // Send Tx burst command over I2C bus cmd[0] = 0x00; // Command register cmd[1] = 0x51; // Ranging results in cm m_i2c.write(m_addr, cmd, 2); // Send ranging burst wait(0.07); // Wait for return echo // Read back range over I2C bus cmd[0] = 0x02; // Address of first echo m_i2c.write(m_addr, cmd, 1, 1); // Send address of first echo m_i2c.read(m_addr, echo, 2); // Read two-byte echo result // Generate PWM mark/space ratio from range data int range = (echo[0]<<8)+echo[1]; return range; } /* * Function: setRangeRegister * Args: rangeVal * Returns: void * Description: Sets the maximum range for which the module waits for an echo * The range is ((rangeVal x 43mm) + 43mm) * The max range is about six meters */ void SRF08::setRangeRegister(char rangeVal) { char cmd[2]; cmd[0] = 0x02; //Range register cmd[1] = rangeVal; //Range value m_i2c.write(m_addr, cmd, 2); } /* * Function: setAddress * Args: address * Returns: void * Description: Sets the address of the module on the I2C bus. The factory default address is 0x0E (224) * The address can have the following values: * E0 | E2 | E4 | E6 ... FC | FE */ void SRF08::setAddress(char address) { char cmd[2]; cmd[0] = 0x00; cmd[1] = 0xA0; m_i2c.write(m_addr, cmd, 2); cmd[1] = 0xAA; m_i2c.write(m_addr, cmd, 2); cmd[1] = 0xA5; m_i2c.write(m_addr, cmd, 2); cmd[1] = address; m_i2c.write(m_addr, cmd, 2); m_addr = address; } /* * Function: readLightIntensity * Args: void * Returns: int lightIntensity * Description: Reads the lightIntensity from the module * The light intensity is updated if a range command is sent, so don't use * this function only */ int SRF08::readLightIntensity() { char cmd[1]; char echo[1]; cmd[0] = 0x01; // Address of light intensity value m_i2c.write(m_addr, cmd, 1, 1); // Send address of first echo m_i2c.read(m_addr, echo, 2); // Read two-byte echo result int lightIntensity = echo[0]; return lightIntensity; }