Read ADC Value and print in (UART) Serial
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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
Term | Description |
---|---|
ADC | Analog-to-Digital Converter – A device or circuit that converts analog signals to digital data. |
Functionality | Converts continuous analog signals into discrete digital values. |
Process | Samples the analog input signal at regular intervals and quantizes the sampled values into digital values. |
Applications | Used in microcontrollers, data acquisition systems, sensors, audio equipment, communication devices, and more. |
Resolution | The number of digital bits used to represent the analog signal. Higher resolution ADCs provide more precise representations. |
Sampling Rate | Determines how frequently the ADC samples the analog input signal. Higher sampling rates enable more accurate representation of fast-changing signals. |
Types | Successive approximation, delta-sigma, pipeline, and flash ADCs are common types, each with specific advantages and applications. |
Interface | Interfaces with digital systems such as microcontrollers or computers, where the digital output values can be processed or stored. |
ADC Pins
Pin | ADC Channel | GPIO Number |
---|---|---|
GPIO32 | ADC1_CH4 | 32 |
GPIO33 | ADC1_CH5 | 33 |
GPIO34 | ADC1_CH6 | 34 |
GPIO35 | ADC1_CH7 | 35 |
GPIO36 | ADC1_CH0 | 36 |
GPIO37 | ADC1_CH1 | 37 |
GPIO25 | ADC2_CH8 | 25 |
GPIO26 | ADC2_CH9 | 26 |
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:
- This section continuously reads the analog value from pin A0 using the
analogRead()
function. - It then prints the value to the serial monitor using
Serial.println()
. - 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
Advantage | Description |
---|---|
Analog Signal Processing | ADCs enable microcontrollers to process analog signals from the physical world, converting them into digital values that can be processed by digital systems. |
Sensor Interfacing | ADCs 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 Conditioning | ADCs 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 Acquisition | ADCs 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. |
Versatility | ADCs come in various resolutions, sampling rates, and input voltage ranges, allowing developers to choose the most suitable ADC for their specific application requirements. |
Integration | Many 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 pinprint
function is the same asuart.write(0, adc.read(0).."\n")
the value to terminal windowadc.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.
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:
Aspect | Description |
---|---|
High Precision | ADCs 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. |
Compatibility | Modern 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 Immunity | Digital 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 Processing | Digital 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 Integration | ADCs 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:
Aspect | Description |
---|---|
Sampling Rate Limitations | ADCs 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 Error | During 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 Cost | High-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 Time | ADCs 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 Limitations | ADCs 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
- 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.
- 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).
- Input Range: The range of analog input voltages that this can accurately convert into digital values without distortion or clipping.
- Accuracy: This refers to how closely the digital output of the ADC matches the true analog input signal.
- Speed: The time taken by the ADC to complete one conversion cycle, including sampling and conversion.
ADC Application
Application | Description |
---|---|
Industrial Automation | ADCs monitor and control analog sensors like temperature, pressure, and flow sensors in industrial automation systems. |
Medical Instrumentation | ADCs convert signals from medical sensors like ECG or blood pressure monitors into digital data for analysis in medical instrumentation. |
Audio Processing | ADCs convert analog audio signals from microphones or musical instruments into digital format for storage or processing in audio applications. |
Automotive Systems | ADCs are integrated into automotive systems for functions like engine control, airbag deployment, and sensor data acquisition for driver assistance systems. |
Communication Systems | ADCs convert analog signals, such as voice or data, into digital format for transmission over digital communication networks in communication systems. |
Test and Measurement | ADCs capture and analyze analog signals with high precision in test and measurement equipment, supporting applications like oscilloscopes and data loggers. |
Consumer Electronics | ADCs in consumer electronics, like smartphones and digital cameras, convert various analog signals into digital data for processing or display. |
Renewable Energy Systems | ADCs monitor and control the generation and distribution of electrical power in renewable energy systems like solar or wind power inverters. |
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