Analog Reading Only 1 and 0 Arduino

This article shows how to read analog inputs with the ESP32 using Arduino IDE. Analog reading is useful to read values from variable resistors similar potentiometers, or analog sensors.

Reading analog inputs with the ESP32 is as like shooting fish in a barrel equally using the analogRead(GPIO) function, that accepts equally argument, the GPIO you want to read.

Nosotros likewise have other tutorials on how to use analog pins with ESP board:

• ESP8266 ADC – Read Analog Values with Arduino IDE, MicroPython and Lua
• ESP32 Analog Readings with MicroPython

Sentinel the Video

You can watch the video tutorial or keep reading this folio for the written instructions.

Analog Inputs (ADC)

Reading an analog value with the ESP32 means you tin measure varying voltage levels between 0 V and 3.3 V.

The voltage measured is and so assigned to a value betwixt 0 and 4095, in which 0 V corresponds to 0, and 3.3 V corresponds to 4095. Any voltage between 0 Five and 3.3 V volition be given the corresponding value in betwixt.

ADC is Non-linear

Ideally, yous would expect a linear behavior when using the ESP32 ADC pins. Withal, that doesn't happen. What you'll get is a behavior as shown in the following chart:

This beliefs means that your ESP32 is not able to distinguish 3.three Five from three.2 5. Yous'll get the same value for both voltages: 4095.

The same happens for very low voltage values: for 0 5 and 0.1 V you'll get the same value: 0. You need to go on this in heed when using the ESP32 ADC pins.

At that place's a discussion on GitHub about this subject.

analogRead() Function

Reading an analog input with the ESP32 using the Arduino IDE is as simple as using theanalogRead() function. Information technology accepts every bit argument, the GPIO yous want to read:

          analogRead(GPIO);        

The ESP32 supports measurements in eighteen different channels. Only 15 are available in the DEVKIT V1 DOIT board (version with thirty GPIOs).

Catch your ESP32 board pinout and locate the ADC pins. These are highlighted with a cerise border in the figure below.

Learn more almost the ESP32 GPIOs: ESP32 Pinout Reference.

These analog input pins have 12-flake resolution. This means that when you read an analog input, its range may vary from 0 to 4095.

Note: ADC2 pins cannot be used when Wi-Fi is used. So, if you're using Wi-Fi and yous're having problem getting the value from an ADC2 GPIO, you may consider using an ADC1 GPIO instead, that should solve your problem.

Other Useful Functions

There are other more than advanced functions to use with the ADC pins that can be useful in other projects.

• analogReadResolution(resolution): set the sample bits and resolution. It can exist a value between 9 (0 – 511) and 12 bits (0 – 4095). Default is 12-bit resolution.
• analogSetWidth(width): set the sample bits and resolution. It tin can be a value betwixt 9 (0 – 511) and 12 bits (0 – 4095). Default is 12-chip resolution.
• analogSetCycles(cycles): set the number of cycles per sample. Default is 8. Range: 1 to 255.
• analogSetSamples(samples): set the number of samples in the range. Default is 1 sample. It has an effect of increasing sensitivity.
• analogSetClockDiv(attenuation): prepare the divider for the ADC clock. Default is 1. Range: 1 to 255.
• analogSetAttenuation(attenuation): sets the input attenuation for all ADC pins. Default is ADC_11db. Accustomed values:
  • ADC_0db: sets no attenuation. ADC can measure upwards to approximately 800 mV (1V input = ADC reading of 1088).
  • ADC_2_5db: The input voltage of ADC volition be attenuated, extending the range of measurement to up to approx. 1100 mV. (1V input = ADC reading of 3722).
  • ADC_6db: The input voltage of ADC will exist attenuated, extending the range of measurement to up to approx. 1350 mV. (1V input = ADC reading of 3033).
  • ADC_11db: The input voltage of ADC will be attenuated, extending the range of measurement to up to approx. 2600 mV. (1V input = ADC reading of 1575).
• analogSetPinAttenuation(pin, attenuation): sets the input attenuation for the specified pin. The default is ADC_11db. Attenuation values are the aforementioned from previous function.
• adcAttachPin(pin): Attach a pin to ADC (too clears any other analog style that could exist on). Returns TRUE or Imitation result.
• adcStart(pivot), adcBusy(pivot) and resultadcEnd(pin): starts an ADC convertion on attached pivot's coach. Cheque if conversion on the pin'due south ADC motorbus is currently running (returns TRUE or FALSE). Become the result of the conversion: returns 16-flake integer.

There is a very skilful video explaining these functions that y'all can watch here.

Read Analog Values from a Potentiometer with ESP32

To run across how everything ties together, we'll make a simple example to read an analog value from a potentiometer.

For this example, y'all need the post-obit parts:

• ESP32 DOIT DEVKIT V1 Board (read All-time ESP32 development boards)
• Potentiometer
• Breadboard
• Jumper wires

Y'all can use the preceding links or get directly to MakerAdvisor.com/tools to notice all the parts for your projects at the all-time cost!

Schematic

Wire a potentiometer to your ESP32. The potentiometer middle pivot should be continued to GPIO 34. You can employ the post-obit schematic diagram every bit a reference.

Code

Nosotros'll program the ESP32 using Arduino IDE, so make sure you take the ESP32 add-on installed before proceeding:

• Windows instructions – ESP32 Board in Arduino IDE
• Mac and Linux instructions – ESP32 Lath in Arduino IDE

Open your Arduino IDE and copy the following code.

          // Potentiometer is connected to GPIO 34 (Analog ADC1_CH6)  const int potPin = 34;  // variable for storing the potentiometer value int potValue = 0;  void setup() {   Serial.begin(115200);   filibuster(1000); }  void loop() {   // Reading potentiometer value   potValue = analogRead(potPin);   Series.println(potValue);   filibuster(500); }                  

View raw code

This code simply reads the values from the potentiometer and prints those values in the Serial Monitor.

In the code, you start by defining the GPIO the potentiometer is connected to. In this case, GPIO 34.

          const int potPin = 34;        

In the setup(), initialize a serial communication at a baud charge per unit of 115200.

          Serial.begin(115200);        

In the loop(), use the analogRead()office to read the analog input from the potPin.

          potValue = analogRead(potPin);        

Finally, print the values read from the potentiometer in the serial monitor.

          Serial.println(potValue);        

Upload the code provided to your ESP32. Make certain you lot have the right board and COM port selected in the Tools carte.

Testing the Example

After uploading the code and pressing the ESP32 reset button, open the Serial Monitor at a baud rate of 115200. Rotate the potentiometer and run across the values irresolute.

The maximum value you'll get is 4095 and the minimum value is 0.

Wrapping Up

In this article you've learned how to read analog inputs using the ESP32 with the Arduino IDE. In summary:

• The ESP32 DEVKIT V1 DOIT board (version with thirty pins) has 15 ADC pins you can utilize to read analog inputs.
• These pins have a resolution of 12 $.25, which means you tin get values from 0 to 4095.
• To read a value in the Arduino IDE, you simply use the analogRead() function.
• The ESP32 ADC pins don't take a linear behavior. You'll probably won't be able to distinguish between 0 and 0.1V, or between 3.2 and 3.3V. You need to keep that in mind when using the ADC pins.

We hope y'all've discover this brusk guide useful. If you want to learn more about the ESP32, enroll in our class: Larn ESP32 with Arduino IDE.

Other ESP32 guides that you may likewise like:

• ESP32 OLED Display with Arduino IDE
• ESP32 with DHT Temperature and Humidity Sensor using Arduino IDE
• ESP32 Web Server with DHT readings
• 20+ ESP32 Projects and Tutorials

Thanks for reading.

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Source: https://randomnerdtutorials.com/esp32-adc-analog-read-arduino-ide/

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