SRF08 Libraray
Dependents: mbedDemoDisplay mbedDemoDisplay Roaming SRF08HelloWorld ... more
Diff: SRF08.cpp
- Revision:
- 0:752fc2753b90
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/SRF08.cpp Mon Aug 09 16:19:08 2010 +0000 @@ -0,0 +1,67 @@ + +/* +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" + + +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] = 0x1C; // Set max range about 100cm + m_i2c.write(m_addr, cmd, 2); + cmd[0] = 0x01; // Receiver gain register + cmd[1] = 0x1B; // Set max receiver gain + m_i2c.write(m_addr, cmd, 2); + +} + +SRF08::~SRF08() { + +} + +float 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 + float range = (echo[0]<<8)+echo[1]; + + return range; +}