├── ESP32_ADC_Voltage_Measurement.ino
└── README.md


/ESP32_ADC_Voltage_Measurement.ino:
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 1 | // 0 - 5 volts range Example
 2 | 
 3 | void setup() {
 4 |   Serial.begin(115200);
 5 | }
 6 | 
 7 | void loop() {
 8 |   Serial.println(readVoltage(),1);
 9 |   float BatteryVoltage = readVoltage();
10 |   delay(1000);
11 | }
12 | 
13 | float readVoltage(){
14 |   #define constant 5.9; // 0-5v range example
15 |   // #define constant 7.1;   // 0-6v   range
16 |   // #define constant 14.6;  // 0-12v  range
17 |   // #define constant 18.5;  // 0-15v  range
18 |   // #define constant 30.1;  // 0-24v  range
19 |   // #define constant 38.1;  // 0-30v  range
20 |   // #define constant 64.5;  // 0-50v  range
21 |   // #define constant 130.0; // 0-100v range
22 |   float ADCvoltage = (float)analogRead(36) / 4095 * constant;
23 |   return ADCvoltage;         // 0-5v   range unless constant is changed
24 | }
25 | 


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/README.md:
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 1 | # ESP32-ADC-Voltage-Measurement
 2 | Using the ADC to measure voltage
 3 | 
 4 | The function that corrects for the ESP32 ADC input impedance loading of an attached voltage divder. I have estimated the ESp32 ADC input impedance to be 1.3Mohms
 5 |  
 6 |   #define constant 5.9; 
 7 |   
 8 |   // 0-5v range example, should be a factor of 5, but loading increases it to 5.9
 9 |   
10 |   // defined constant 5.9   // 0-5v   range
11 |   
12 |   // #define constant 7.1   // 0-6v   range
13 |   
14 |   // #define constant 14.6  // 0-12v  range
15 |   
16 |   // #define constant 18.5  // 0-15v  range
17 |   
18 |   // #define constant 30.1  // 0-24v  range
19 |     
20 |   // #define constant 38.1  // 0-30v  range
21 |   
22 |   // #define constant 64.5  // 0-50v  range
23 |   
24 |   // #define constant 130.0 // 0-100v range
25 |   
26 | float readVoltage(){
27 | 
28 |   float ADCvoltage = (float)analogRead(36) / 4095 * constant;
29 |   
30 |   return ADCvoltage * constant; // 0-5v   range
31 | }
32 | 
33 | // I cannot fully explain why as input voltage increases and effective load on the voltage divider by the ESP32 decreases that the constant offset increases, it should be the opposite!
34 | 


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