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ESP32 ArduinoCore Interface – ADC

The “ESP32 ArduinoCore Interface – ADC” provides a seamless integration between the ESP32 microcontroller and the Arduino development environment, specifically focusing on the Analog-to-Digital Converter (ADC) functionality.

ADC

TermDescription
ADCAnalog-to-Digital Converter – A device or circuit that converts analog signals to digital data.
FunctionalityConverts continuous analog signals into discrete digital values.
ProcessSamples the analog input signal at regular intervals and quantizes the sampled values into digital values.
ApplicationsUsed in microcontrollers, data acquisition systems, sensors, audio equipment, communication devices, and more.
ResolutionThe number of digital bits used to represent the analog signal. Higher resolution ADCs provide more precise representations.
Sampling RateDetermines how frequently the ADC samples the analog input signal. Higher sampling rates enable more accurate representation of fast-changing signals.
TypesSuccessive approximation, delta-sigma, pipeline, and flash ADCs are common types, each with specific advantages and applications.
InterfaceInterfaces with digital systems such as microcontrollers or computers, where the digital output values can be processed or stored.

ADC Pins

PinADC ChannelGPIO Number
GPIO32ADC1_CH432
GPIO33ADC1_CH533
GPIO34ADC1_CH634
GPIO35ADC1_CH735
GPIO36ADC1_CH036
GPIO37ADC1_CH137
GPIO25ADC2_CH825
GPIO26ADC2_CH926

This table lists the ADC pins available on the ESP32 microcontroller along with their corresponding ADC channels and GPIO numbers.

Code

/*
  AnalogReadSerial
  Reads an analog input on pin 0, prints the result to the serial monitor.
  Graphical representation is available using serial plotter (Tools > Serial Plotter menu)
  Attach the center pin of a potentiometer to pin A0, and the outside pins to +5V and ground.

  This example code is in the public domain.
*/

// the setup routine runs once when you press reset:
void setup() {
  // initialize serial communication at 9600 bits per second:
  Serial.begin(9600);
}

// the loop routine runs over and over again forever:
void loop() {
  
  // read the input on analog pin 0:
  int sensorValue = analogRead(A0);
  // print out the value you read:
  
  Serial.println(sensorValue);
  delay(1);        // delay in between reads for stability
}

Code Explanation of ESP32 ArduinoCore Interface ADC

Code Purpose: Reading an analog input from pin A0 and printing the value to the serial monitor.

Setup Routine: This part of the code initializes serial communication at a baud rate of 9600 bits per second.

   // the setup routine runs once when you press reset:
   void setup() {
     // initialize serial communication at 9600 bits per second:
     Serial.begin(9600);
   }

Loop Routine:

  1. This section continuously reads the analog value from pin A0 using the analogRead() function.
  2. It then prints the value to the serial monitor using Serial.println().
  3. A small delay of 1 millisecond is added between reads for stability using delay().
   // the loop routine runs over and over again forever:
   void loop() {
     // read the input on analog pin 0:
     int sensorValue = analogRead(A0);
     // print out the value you read:
     Serial.println(sensorValue);
     delay(1);        // delay in between reads for stability
   }

Overall Functionality: This code can be useful for testing analog sensors or for basic data-logging applications.

Advantage of ESP32 ArduinoCore Interface ADC

AdvantageDescription
Analog Signal ProcessingADCs enable microcontrollers to process analog signals from the physical world, converting them into digital values that can be processed by digital systems.
Sensor InterfacingADCs facilitate interfacing with various sensors that produce analog output, such as temperature sensors, light sensors, and pressure sensors, allowing accurate measurement and response to real-world phenomena.
Signal ConditioningADCs can be used for signal conditioning tasks, including amplification, filtering, and noise reduction, before converting analog signals to digital form, improving accuracy and reliability of measured data.
Data AcquisitionADCs enable microcontrollers to acquire data from analog sources at high speeds and with high precision, suitable for applications such as data logging, instrumentation, and control systems.
VersatilityADCs come in various resolutions, sampling rates, and input voltage ranges, allowing developers to choose the most suitable ADC for their specific application requirements.
IntegrationMany microcontrollers, including the ESP32, feature built-in ADCs, eliminating the need for external ADC components and reducing system complexity and cost.

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ESP8266 NodeMCU Interface – ADC

ADC

ESP8266 with  ADC Interface

                    This the simple example of ADC with ESP8266. ESP8266 have a in-build ACD unit with 10 bit resolution(10bits-0 to 1024 steps), so no need to add a external ADC converter ICs. if your beginner try this below codes and understand the ADC with ESP8266. I used Ai-thinger’s ESP-12F module(not used NodeMCU Dev Board) wit USB to UART Programmer and NodeMCU firmware. but you can also use any other firmware like Arduino code, Man-goose OS to do this. In this experiment used 3 NodeMCU module libraries are UART (for printing), Timer(for looping), and ADC Module. So your NodeMCU firmware should have this modules. NodeMCU only support only one ACD pin. ADC bin converts voltage from 0 to 3.3 according to 0- 1024 values(10bit resolution)

  •  Required Hardware Components :  2x USB to UART converter programmer, 1x ESP8266 Module(Used Ai-Thinker’s ESP-12F module), 1x Variable resistor  (Pot-10k)
  • Required software tools : ESPlorer IDE Tool,

Note : if you use NodeMCU Dev board don’t need ESP8266 Ai-Thinkers Module and UART Programmer. Because NodeMCU Dev Board have already Programmer.

Circuit Diagram

 

Code

  • EX  :tmr.alarm(0,500,1, function printf(adc.read(0)) end)
  • tmr.alarm function is like a loop for 500microseconds, So every microseconds once that ESP read the ADC value from that pin
  • print function is the same as uart.write(0, adc.read(0).."\n") the value to terminal window
  • adc.read  read the ADC value.

Results

 



 

ESP8266 Arduino-Core Interface – ADC

ADC

Required

  • Required Hardware – ESP8266 with Programmer (or)  NodeMCU Dev Kit
  • Required Software Tools  – Arduino IDE with ESP8266 Core

Circuit

Code

/* 
  http://www.ArunEworld.com/Embedded/ESPressif/ESP8266/ESP8266_Arduino-Core/
  Tested By  : Arun(20170219)
  Example Name : AEW_ADC-Interface.ino
 */
 /*
  AnalogReadSerial
  Reads an analog input on pin 0, prints the result to the serial monitor.
  Graphical representation is available using serial plotter (Tools > Serial Plotter menu)
  Attach the center pin of a potentiometer to pin A0, and the outside pins to +5V and ground.

  This example code is in the public domain.
*/

// the setup routine runs once when you press reset:
void setup() {
  // initialize serial communication at 9600 bits per second:
  Serial.begin(9600);
}

// the loop routine runs over and over again forever:
void loop() {
  // read the input on analog pin 0:
  int sensorValue = analogRead(A0);
  // print out the value you read:
  Serial.println(sensorValue);
  delay(1);        // delay in between reads for stability
}

 

Result

3
2
3
4
3
3
4
3
2
3
4
2
2

 


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Embedded Interface – ADC

The analog-to-digital converter (ADC) converts the continuous analog signal into a flow of digital values. To achieve this, the converter must establish the rate at which new digital values sample from the analog signal. This rate is termed the sampling rate or sampling frequency of the converter.

Read more: Embedded Interface – ADC

ADC

A successive approximation ADC uses a comparator to narrow the input voltage range. Digital systems store values in binary format, with resolution usually in bits, often a power of two. Furthermore, one can define resolution electrically and represent it in volts. Consequently, we call the smallest voltage change needed to alter the output code level the least significant bit.

ADC Advantage:

AspectDescription
High PrecisionADCs provide high precision in converting analog signals into digital form, thereby ensuring an accurate representation of the original signal. Consequently, this precision allows for reliable data processing and analysis.
CompatibilityModern digital systems find digital signals more compatible, as they can easily process, transmit, and store them using digital devices. Additionally, this compatibility enhances the efficiency and effectiveness of digital systems in various applications.
Noise ImmunityDigital signals are less susceptible to noise interference during transmission or processing compared to analog signals. Consequently, this leads to better signal integrity and more reliable data transmission in digital communication systems.
Signal ProcessingDigital signals allow for advanced signal processing techniques such as filtering, modulation, and encryption. As a result, this enhances the versatility of digital systems, enabling them to adapt to a wide range of applications and requirements.
Ease of IntegrationADCs can be integrated into various electronic devices, providing a seamless interface between analog sensors or sources and digital processing units. Consequently, this integration enhances the functionality and performance of electronic systems by enabling accurate and efficient conversion of analog signals into digital data.

Disadvantage:

AspectDescription
Sampling Rate LimitationsADCs are limited by their sampling rate, which determines the maximum frequency of signals they can accurately capture. Consequently, inadequate sampling rates can lead to aliasing and loss of signal fidelity, compromising the accuracy of the digital representation of analog signals.
Quantization ErrorDuring the analog-to-digital conversion process, quantization error can occur. Consequently, this can lead to inaccuracies in the representation of the original analog signal, affecting the fidelity of the digital output.
Complexity and CostHigh-resolution ADCs, capable of accurately capturing fine details in analog signals, can be complex and expensive. Consequently, for applications demanding high-speed or high-precision conversion, these ADCs may pose challenges due to their complexity and cost.
Conversion TimeADCs require a finite amount of time to convert analog signals into digital form. As a result, this causes latency in real-time systems or applications that demand rapid signal processing.
Dynamic Range LimitationsADCs have a limited dynamic range, which can affect their ability to accurately capture signals with a wide range of amplitudes. Consequently, this limitation can potentially cause distortion or loss of information in the converted signal, particularly when dealing with signals of varying amplitudes.

Features of ADC

  1. Resolution: This refers to the number of bits used to represent the analog input in digital form. Higher resolution ADCs can represent smaller voltage changes, providing greater precision.
  2. Sampling Rate: The rate at which the ADC samples the analog input signal and converts it into digital form. It is typically measured in samples per second (SPS) or Hertz (Hz).
  3. Input Range: The range of analog input voltages that this can accurately convert into digital values without distortion or clipping.
  4. Accuracy: This refers to how closely the digital output of the ADC matches the true analog input signal.
  5. Speed: The time taken by the ADC to complete one conversion cycle, including sampling and conversion.

ADC Application

ApplicationDescription
Industrial AutomationADCs monitor and control analog sensors like temperature, pressure, and flow sensors in industrial automation systems.
Medical InstrumentationADCs convert signals from medical sensors like ECG or blood pressure monitors into digital data for analysis in medical instrumentation.
Audio ProcessingADCs convert analog audio signals from microphones or musical instruments into digital format for storage or processing in audio applications.
Automotive SystemsADCs are integrated into automotive systems for functions like engine control, airbag deployment, and sensor data acquisition for driver assistance systems.
Communication SystemsADCs convert analog signals, such as voice or data, into digital format for transmission over digital communication networks in communication systems.
Test and MeasurementADCs capture and analyze analog signals with high precision in test and measurement equipment, supporting applications like oscilloscopes and data loggers.
Consumer ElectronicsADCs in consumer electronics, like smartphones and digital cameras, convert various analog signals into digital data for processing or display.
Renewable Energy SystemsADCs monitor and control the generation and distribution of electrical power in renewable energy systems like solar or wind power inverters.

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