Diff: SRF02.cpp

Revision:

0:b729d2ce03bd

Child:

2:43910fab41ca

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SRF02.cpp	Sun Mar 08 14:15:29 2015 +0000
@@ -0,0 +1,55 @@
+/**
+@file SRF02.cpp
+
+@brief Member functions implementations
+
+*/
+#include "mbed.h"
+#include "SRF02.h"
+
+SRF02::SRF02(PinName sdaPin, PinName sclPin)
+{
+    i2c = new I2C(sdaPin,sclPin); // create new I2C instance and initialise
+    i2c->frequency(400000);       // I2C Fast Mode - 400kHz
+    leds = new BusOut(LED4,LED3,LED2,LED1);
+
+}
+
+int SRF02::getDistanceCm()
+{
+    char data[2];
+    
+    // need to send CM command to command register
+    data[0] = CMD_REG;
+    data[1] = CM_CMD;
+    int ack = i2c->write(SRF02_W_ADD,data,2);  
+    if (ack)
+        error();  // if we don't receive acknowledgement, flash error message
+        
+    // this will start the sensor ranging, the datasheet suggests a delay of at least 65 ms before reading the result
+    wait_ms(70);
+    
+    // we can now read the result - tell the sensor we want the high byte
+    char reg = RANGE_H_REG;   
+    ack = i2c->write(SRF02_W_ADD,&reg,1);  
+    if (ack)
+        error();  // if we don't receive acknowledgement, flash error message
+    
+    // if we read two bytes, the register is automatically incremented (H and L)
+    ack = i2c->read(SRF02_R_ADD,data,2); 
+    if (ack)
+        error();  // if we don't receive acknowledgement, flash error message
+
+    // high byte is first, then low byte, so combine into 16-bit value
+    return (data[0] << 8) | data[1];
+}
+
+void SRF02::error()
+{
+    while(1) {
+        leds->write(15);
+        wait(0.1);
+        leds->write(0);
+        wait(0.1);    
+    }    
+}
\ No newline at end of file