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;
+}