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-
- /*
- 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;
- }
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