Delay to Read Adc Values Analog Devices

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 easy as using the analogRead(GPIO) function, that accepts as argument, the GPIO you want to read.

We besides 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

Watch the Video

You tin sentinel the video tutorial or keep reading this folio for the written instructions.

Analog Inputs (ADC)

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

The voltage measured is then assigned to a value between 0 and 4095, in which 0 V corresponds to 0, and 3.3 V corresponds to 4095. Any voltage between 0 V and 3.iii V volition be given the corresponding value in between.

ADC is Not-linear

Ideally, you would expect a linear beliefs when using the ESP32 ADC pins. Nonetheless, that doesn't happen. What y'all'll go is a behavior as shown in the following chart:

This behavior ways that your ESP32 is non able to distinguish 3.iii V from 3.2 Five. You'll become the same value for both voltages: 4095.

The same happens for very low voltage values: for 0 V and 0.ane V yous'll get the aforementioned value: 0. You need to keep this in mind 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 elementary as using theanalogRead() part. Information technology accepts as argument, the GPIO you lot want to read:

          analogRead(GPIO);        

The ESP32 supports measurements in 18 different channels. Only 15 are available in the DEVKIT V1 DOIT board (version with 30 GPIOs).

Take hold of your ESP32 board pinout and locate the ADC pins. These are highlighted with a red border in the effigy below.

Larn more about the ESP32 GPIOs: ESP32 Pinout Reference.

These analog input pins have 12-bit resolution. This ways 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 you'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 avant-garde functions to use with the ADC pins that can be useful in other projects.

• analogReadResolution(resolution): set the sample bits and resolution. Information technology tin exist a value between 9 (0 – 511) and 12 $.25 (0 – 4095). Default is 12-bit resolution.
• analogSetWidth(width): set the sample bits and resolution. It can be a value between 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 issue of increasing sensitivity.
• analogSetClockDiv(attenuation): fix the divider for the ADC clock. Default is ane. Range: 1 to 255.
• analogSetAttenuation(attenuation): sets the input attenuation for all ADC pins. Default is ADC_11db. Accepted values:
  • ADC_0db: sets no attenuation. ADC can mensurate up to approximately 800 mV (1V input = ADC reading of 1088).
  • ADC_2_5db: The input voltage of ADC will exist 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 adulterate, 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 same from previous part.
• adcAttachPin(pin): Attach a pin to ADC (also clears any other analog way that could be on). Returns True or FALSE upshot.
• adcStart(pin), adcBusy(pivot) and resultadcEnd(pin): starts an ADC convertion on fastened pin'south passenger vehicle. Cheque if conversion on the pin'south ADC bus is currently running (returns TRUE or FALSE). Get the result of the conversion: returns 16-chip integer.

At that place is a very practiced video explaining these functions that you can picket here.

Read Analog Values from a Potentiometer with ESP32

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

For this instance, you demand the following parts:

• ESP32 DOIT DEVKIT V1 Board (read Best ESP32 development boards)
• Potentiometer
• Breadboard
• Jumper wires

You tin utilise the preceding links or get straight to MakerAdvisor.com/tools to find all the parts for your projects at the best price!

Schematic

Wire a potentiometer to your ESP32. The potentiometer heart pin should exist continued to GPIO 34. Yous tin can utilize the post-obit schematic diagram as a reference.

Code

We'll program the ESP32 using Arduino IDE, then make certain you have the ESP32 add-on installed before proceeding:

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

Open up your Arduino IDE and re-create 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.brainstorm(115200);   delay(1000); }  void loop() {   // Reading potentiometer value   potValue = analogRead(potPin);   Series.println(potValue);   delay(500); }                  

View raw code

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

In the lawmaking, you offset by defining the GPIO the potentiometer is connected to. In this example, GPIO 34.

          const int potPin = 34;        

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

          Serial.begin(115200);        

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

          potValue = analogRead(potPin);        

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

          Series.println(potValue);        

Upload the code provided to your ESP32. Make sure yous accept the right board and COM port selected in the Tools menu.

Testing the Example

After uploading the code and pressing the ESP32 reset push button, open the Series Monitor at a baud rate of 115200. Rotate the potentiometer and run into the values changing.

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

Wrapping Up

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

• The ESP32 DEVKIT V1 DOIT board (version with 30 pins) has 15 ADC pins you can employ to read analog inputs.
• These pins take a resolution of 12 bits, which means you lot can get values from 0 to 4095.
• To read a value in the Arduino IDE, you simply apply 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 iii.two and 3.3V. You need to keep that in mind when using the ADC pins.

We hope you've discover this short guide useful. If yous want to learn more about the ESP32, enroll in our course: Learn ESP32 with Arduino IDE.

Other ESP32 guides that you may besides like:

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