Diff: Ohmmeter_Code.cpp

Revision:

2:6077294f7007

Parent:

1:5aacfef29ca8

Child:

3:b6e887e4ac75

--- a/Ohmmeter_Code.cpp	Wed Apr 01 19:21:27 2020 +0000
+++ b/Ohmmeter_Code.cpp	Wed Apr 01 19:45:59 2020 +0000
@@ -1,5 +1,10 @@
 /*
-hello
+the code is set up to auto range for different known resistance value
+it will base the case statement on its original Restimate value
+the voltage drop across the transistor is different for each case
+this value was found using simulations from LTspice 
+a value for Runkown will be printed on the screen and this will be in a 
+contunious loop from the switch
 */
 //Case x:
 
@@ -15,29 +20,29 @@
 
 AnalogIn vo(A0);
 
-double vout = (3.3 * vo)/ 4095;
+double vout = (3.3 * vo)/ 4095; //converts analog read from bits to voltage
 
 double rest;
 
 double vt;
 
-rest = (vout * 100) / (3.3 - vout);
-
+rest = (vout * 100) / (3.3 - vout); //rest is an estimate as it does not account for the voltage drop in transistor
+                                    //this essentially  decides what pin we will use for final value
 switch (rest)
 {
     case 550: 
-    vt = 0.0647875;
+    vt = 0.0647875;                   // vt is based off ltspice values from simulations
     runknown = (vout * 100) / (3.3 - vt - vout);
     if (runknown < 10){
-        lcd.printf("Out of Range");
+        lcd.printf("Out of Range");       //this will be out of the range of our design parameters
     }
     else{
-        lcd.locate(0,1);
-        lcd.printf("%u Ω", runknown);
+        lcd.locate(0,1);                 
+        lcd.printf("%u Ω", runknown);   // prints on the second row of the LCD screen 
         }
         break;
         
-    case 5500:
+    case 5500:                          // this case is for if R is in a different range 
     vt = 0.0189; 
     100ohm = 1;
     1kohm = 0;
@@ -45,10 +50,10 @@
     runknown = (vout * 1000) / (3.3 - vt - vout); 
     lcd.locate(0,1);
     if (runknown < 1000){
-        lcd.printf("%u Ω", runknown);
-    }
+        lcd.printf("%u Ω", runknown);     
+    } // this if correct runknown to the appropriate magnitude 
     else {
-        runknown = runknown / 1000;
+        runknown = runknown / 1000; //runkown is now printed in KΩ
         lcd.printf("%.2f kΩ", runknown);
         break;
         
@@ -77,7 +82,7 @@
         lcd.printf("%.2f kΩ", runknown);
         }
     else {
-        runknown = runknown / 1000000;
+        runknown = runknown / 1000000;        // this will change the magnitude to MΩ
         lcd.printf("%.2f MΩ", runknown);
         break;
         
@@ -107,7 +112,7 @@
         
     default:
     lcd.locate(0,1);
-    lcd.printf("Out of Range");
+    lcd.printf("Out of Range"); // this will apear if runkown is outside the design parameters 
     break;
     
 }    
\ No newline at end of file