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 signal is continuous in time and it is necessary to convert this to a flow of digital values. It is therefore required to define the rate at which new digital values are sampled from the analog signal. The rate of new values is called the sampling rate or sampling frequency of the converter.
- The most common ways for implementing ADC are direct conversion, successive approximation, ramp compare, Wilkinson, integrating, delta encoded, pipelined, sigma-delta, time-interleaved, intermediate FM stage, other types.
- A successive-approximation ADC uses a comparator to successively narrow a range that contains the input voltage.
- The values are usually stored electronically in binary form, so the resolution is usually expressed in bits.
- The number of discrete values available, or levels, is assumed to be the power of two.
- Resolution can also be defined electrically and expressed in volts. The minimum change in voltage required to guarantee a change in the output code level is called the least significant bit.
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