Diff: SRF02.cpp

Revision:

0:862f11d627f9

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SRF02.cpp	Sun Jul 10 16:40:35 2011 +0000
@@ -0,0 +1,52 @@
+
+
+/*Library for SRF02 ultrasonic range finder*/
+#include "SRF02.h"
+
+
+
+SRF02::SRF02(PinName sda, PinName scl, int addr) : m_i2c(sda, scl), m_addr(addr){
+    //no initialisation code required here
+    }
+    
+SRF02::~SRF02(){
+
+}
+
+float SRF02::measurecm() {
+   float result = dosonar(0x51);
+   return result;
+}
+
+float SRF02::measureus() {
+   float result = dosonar(0x52);
+   return result;
+}
+
+float SRF02::measurein() {
+   float result = dosonar(0x50);
+   return result;
+}
+
+
+float SRF02::dosonar(char rangetype){
+    //local variables
+    const char m_addr = 0xE0;  //srf02 default slave address
+    char commandsequence[2];
+    
+    // Get range data from SRF02 in cm
+        // Send Tx burst command over I2C bus
+        commandsequence[0] = 0x00;               // Command register
+        commandsequence[1] = rangetype;          // Ranging results type
+        m_i2c.write(m_addr, commandsequence, 2); // Request ranging from sensor
+        wait(0.07);  // Average wait time for sonar pulse and processing
+        // Read back range over I2C bus
+        commandsequence[0] = 0x02;                   // 
+        m_i2c.write(m_addr, commandsequence, 1, 1);  // 
+        m_i2c.read(m_addr, commandsequence, 2);             // Read two-byte echo result
+        //combine upper and lower bytes in to a single value
+        float range = ((commandsequence[0] << 8) + commandsequence[1]);
+        return range;
+
+}
+