Diff: SRF08.cpp

Revision:

0:4e0a8193b92e

Child:

1:76fb116fa28d

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SRF08.cpp	Thu Jul 05 09:53:18 2012 +0000
@@ -0,0 +1,140 @@
+
+/*
+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;
+}