Diff: SRF02.cpp

Revision:

2:98253d9cbccd

Parent:

0:b729d2ce03bd

--- a/SRF02.cpp	Sun Mar 08 14:21:40 2015 +0000
+++ b/SRF02.cpp	Mon May 11 16:35:20 2015 +0000
@@ -44,8 +44,37 @@
     return (data[0] << 8) | data[1];
 }
 
-void SRF02::error()
+int SRF02::getDistanceInch()
 {
+    char data[2];
+    
+    // need to send CM command to command register
+    data[0] = CMD_REG;
+    data[1] = INCH_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);