Finally a way to sort out your resistors

1// lazyRmeter by FEDERICO VIVALDI all references to OLE display removed  - pins relocated
2// lazyRmeter_v2_16x2 semplified by F.Stella 20200221 for UNO  and serial print to be ported to simple 16x2 display
3
4// LCD 16x2 code - example  added 9 Jul 2009 by Tom Igoe - modFS2020
5//include the LCD library code:
6#include  <LiquidCrystal.h>
7
8// initialize the library by associating any needed LCD  interface pin
9// with the arduino pin number it is connected to
10const int  rs = 12, en = 11, d4 = 5, d5 = 4, d6 = 3, d7 = 2;
11LiquidCrystal lcd(rs, en, d4,  d5, d6, d7);
12
13//Resistenze di comparazione sul circuito:
14//compR1 = 100   Ohm  collegata a PIN  6 (lowest)
15//compR2 =   1  kOhm  collegata a PIN  7
16//compR3  =  10  kOhm  collegata a PIN  8
17//compR4 = 100  kOhm  collegata a PIN  9
18//compR5  =   1  MOhm  collegata a PIN 10 (top)
19
20int R1 = 100; 
21int R2 = 1000;
22int  R3 = 10000;
23long R4 = 100000;
24long R5 = 1000000;
25long Rn;
26
27float  Input;
28
29String valore;
30String suffisso;
31float trans;
32
33int compR1  = 6;
34int compR2 = 7;
35int compR3 = 8;
36int compR4 = 9;
37int compR5 = 10;
38
39float  raw = 0;
40float Vout = 0;
41float Ru = 0;
42int analogOhm = A0;
43
44void  setup() {
45  Serial.begin(9600);
46  // set up the LCD's number of columns and  rows:
47  lcd.begin(16, 2);
48  // Print a fixed message title to the LCD.
49  lcd.print("Resistenza da: ");
50}
51
52void loop() {
53    //attivazione  porte a cui sono collegate le resistenze campione
54    pinMode(compR1, OUTPUT);   //parto attivando il pin 2 che va alla resistenza test pi alta da 1M
55    pinMode(compR2,  INPUT);
56    pinMode(compR3, INPUT);
57    pinMode(compR4, INPUT);
58    pinMode(compR5,  INPUT);
59
60    digitalWrite(compR1, HIGH);     //attiva la tensione a 5V sulla  resistenza a 1 MOhm e resistenza da misurare
61    raw = analogRead(analogOhm);    //legge il valore su A0 della tensione su 1 Ohm
62    
63    Rn = R5;       
64    
65    Serial.println(raw);            //DEBUG
66    Serial.println("ref  1M");       //DEBUG
67
68    int rawLimitLow = 350; //originale 350
69    int  rawLimitTop = 850; //originale 800
70   
71    if (raw < rawLimitLow || raw >  rawLimitTop){
72      digitalWrite(compR1, LOW);
73      pinMode(compR1, INPUT);
74      pinMode(compR2, OUTPUT);
75      digitalWrite(compR2, HIGH);
76      raw  = analogRead(analogOhm);
77      Rn = R4;
78      
79      Serial.println(raw);
80      Serial.print("ref 100k: ");
81      Serial.println(Rn);
82
83      if  (raw < rawLimitLow || raw > rawLimitTop){
84        digitalWrite(compR2, LOW);
85        pinMode(compR2, INPUT);
86        pinMode(compR3, OUTPUT);
87        digitalWrite(compR3,  HIGH);
88        raw = analogRead(analogOhm);
89        Rn = R3;
90        
91        Serial.println(raw);
92        Serial.println("ref 10k");
93
94        if  (raw < rawLimitLow || raw > rawLimitTop){
95          digitalWrite(compR3, LOW);
96          pinMode(compR3, INPUT);
97          pinMode(compR4, OUTPUT);
98          digitalWrite(compR4,  HIGH);
99          raw = analogRead(analogOhm);
100          Rn = R2;
101          
102          Serial.println(raw);
103          Serial.println("ref 1k");
104          
105          if (raw < rawLimitLow || raw > rawLimitTop){
106            digitalWrite(compR4,  LOW);
107            pinMode(compR4, INPUT);
108            pinMode(compR5, OUTPUT);
109            digitalWrite(compR5, HIGH);
110            raw = analogRead(analogOhm);
111            Rn = R1;
112            
113            Serial.println(raw);      //  DEBUG
114            Serial.println("ref 100");// DEBUG
115          }
116        }
117      }
118    }
119
120    Vout = 5*(raw/1024);
121   
122    Ru = (Rn*Vout)/(5-Vout);
123    Serial.print("Ru: ");             // DEBUG
124    Serial.println(Ru);               //  DEBUG
125
126    String resOhm = OhmFormattingFunction(Ru);
127    delay(1000);  
128    
129    Serial.print("Resistenza da: ");  // DEBUG
130    Serial.println(resOhm);           // DEBUG
131
132    lcd.setCursor(0,1);   
133    lcd.print(resOhm);
134}
135
136String  OhmFormattingFunction(float Input) {
137    //FS 20200223 v0 - Ohm values formatting  function **
138
139    String Result;
140    
141    if (Input < 80) {
142      valore  = (String(round(Input)));
143      suffisso = " ";    
144    }
145    else if  (Input < 800){
146      valore = (String(10*round(Input/10)));
147      suffisso  = " Ohm";          
148    } 
149    else if (Input < 9000){
150      trans =  float(round(Input/100))/10;
151      valore = (String(trans));
152      suffisso  = " KOhm";          
153    }
154    else if (Input < 90000){
155      valore  = (String(10*round(Input/10000)));
156      suffisso = " KOhm";          
157    }
158    else if (Input < 900000){
159      valore = (String(10*round(Input/10000)));
160      suffisso = " KOhm";          
161    }
162    else {
163      valore = (String(round(Input/1000000)));
164      suffisso = " MOhm";          
165    }    
166    Result = valore + suffisso;
167    return Result;
168}
169