Introduction: DC Motor Speed Control With ESP32

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We’ll discuss today about the H Bridge, and how to control the speed of a DC motor with an ESP32 LoRa with display. I'll introduce you to an H-bridge speed control using MOSFET, and then we’ll apply that control to an engine to evaluate its behavior. I specifically like the car glass engine, as it consumes a reasonable current of around 2 amps. However, it has a lot of torque force. It also has an endless thread with a gear that gives it good mechanical resistance.

If you haven’t seen it yet, watch this video now: Super Driver from 1 to 200 amps for DC Motor. Here, I teach about Bridge H with MOSFETs.

Step 1: Demonstration

Step 2: Resources Used

• One ESP WiFi LoRa 32

• Four IRF1404s

• Three BC337s

• One CD4011

• Resistors

• Two 1uF electrolytic capacitors

• Two diode 1N4148s

• USB cable for ESP

• 12V source for the load used

• Charging (we use an electric glass motor)

• Protoboard

• Wires

• Tachometer or other method to measure RPM

Step 3: Scheme

• This is the scheme used in this example, and it is the same as shown in the H-bridge video with MOSFET

Step 4: Scheme - Bridge H

• The H-bridge will have four IRF1404s arranged so that the activation of a pair will allow current flow in one direction, and the activation of the opposite pair will reverse the direction.

• We indicate the torque that must be activated at the same time by the DIR A and DIR B inputs, indicating the change of direction of the motor.

Step 5: Diagram - the Voltage Folder

• This is a circuit based on diodes and capacitors that are well-known in electronics.

• It functions primarily as an electron "pump,” pushing electrons through the capacitors to create a higher voltage due to the accumulation of charges.

• At first, a voltage doubler must deliver twice the input voltage at its output.

• In practice, due to voltage drops, the value obtained was approximately 21.5V. But it was enough for the MOSFET.

Step 6: Schema - Activation - Hardware

• Unlike the last video, this time we have included the control circuit of the states of the H bridge. This is to expand the previous example and guarantee a physical stage of protection against the prohibited state.

• Control inputs will be named:

 EN (from the ENABLE term), connected to the GPIO17 of the ESP.

 DIR, connected to ESP GPIO4.

• We will use a PWM applied to the EN pin to control the amount of energy delivered to the motor and consequently its speed.

• REMEMBER: THERE SHOULD NOT BE SIMULTANEOUS ACTIVATION OF DIR A AND DIR B

Step 7: Capture of Control Circuit Output States

Step 8: ​Procedure

 We’ll write a code that allows us to obtain the RPM value for several PWM values.

 For this, we measure the RPM using a digital tachometer.

 For each PWM value, we’ll measure the engine RPM for 20 seconds

Step 9: Evaluating the Behavior of the Engine

Step 10: Source Code: Mean Curve

Step 11: Speed Adjustment Function

• Using the methods that we have already presented on other occasions, we can obtain a mean curve. The mean curve represents the behavior of the motor in question. From there, relate a value of PWM and RPM.

Mode: normal

Polynomial degree 6, 25 x,y data pairs

Correlation coefficient (r^2) = 9,999194679032e-01

Standard error = 1,643952462530e-01

Output form: C/C++ function:

double f(double x) {

return -5,900718562093e+01

+ 1,080432239400e-01 * x

+ 8,360068942087e-06 * pow(x,2)

+ -4,690449122452e-08 * pow(x,3)

+ 2,352218983798e-11 * pow(x,4)

+ -4,810573531109e-15 * pow(x,5)

+ 3,614465424238e-19 * pow(x,6);

}

Copyright © 2012, P. Lutus -- http://www.arachnoid.com. All Rights Reserved.

Step 12: Source Code

#Includes and #Defines

//Bibliotecas para utilização do display OLED
#include <Wire.h>  // Necessário apenas para o Arduino 1.6.5 e posterior
#include "SSD1306.h" // o mesmo que #include "SSD1306Wire.h"
 
//Os pinos do OLED estão conectados ao ESP32 pelos seguintes GPIO's:
//OLED_SDA -- GPIO4
//OLED_SCL -- GPIO15
//OLED_RST -- GPIO16
 
#define SDA    4
#define SCL   15
#define RST   16 //RST pode ser ajustado por software

Objects, Constants, and Variables

SSD1306  display(0x3c, SDA, SCL, RST); //Instanciando e ajustando os pinos do objeto "display"
 
//PWM usado como oscilador do dobrador de tensão
const int freq_osc = 1000; //Frequencia do PWM
const int canal_osc = 0; // canal do PWM oscilador
const int pin_osc = 21; //GPIO utilizada para o oscilador
const int ciclo = 2048; //ciclo de trabalho de 50%
 
//PWM usado para controle de velocidade
const int freq_vel = 200; //Frequencia do PWM do controle de velocidade
const int canal_vel = 1; // canal do PWM controle de velocidade
const int pin_EN = 17; //Habilita ou desabilita a ponte (controla a velocidade)
const int pin_DIR = 2; //Controla direção
 
//Resolução dos PWM's
const int resolucao = 12; // Resolução (4096 estados)
 
//Intervalo para mudança do PWM
const int intervalo = 200; 
 
//Constante que determinar o valor mínimo para o PWM
const int min_vel = 0;
 
// Variável usada para alternar a direção
boolean dir = false;
 
// variável para armazenar a velocidade atual
int velocidade = 0;

Setup ()

void setup()
{
  //seta a direção dos GPIO
  pinMode(pin_osc, OUTPUT);
  pinMode(pin_DIR, OUTPUT);
  pinMode(pin_EN, OUTPUT);
 
  // Ajusta o PWM do oscilador do dobrador
  ledcSetup(canal_osc, freq_osc, resolucao);
  ledcAttachPin(pin_osc, canal_osc);
  ledcWrite(canal_osc, ciclo);
 
  // Ajusta o PWM de controle de velocidade
  ledcSetup(canal_vel, freq_vel, resolucao);
  ledcAttachPin(pin_EN, canal_vel);
  ledcWrite(canal_vel, velocidade);
 
  //Ajusta a direção para LOW inicialmente
  digitalWrite(pin_DIR, dir);
 
  // Inicia o display
  display.init();
 
  display.flipScreenVertically(); //Vira a tela verticalmente
  display.clear();
  //ajusta o alinhamento para a esquerda
  display.setTextAlignment(TEXT_ALIGN_LEFT);
  //ajusta a fonte para Arial 16
  display.setFont(ArialMT_Plain_16);
}

Loop ()

void loop()
{
  //Varia os estados do PWM do máximo até o valor mínimo em passos de 136.5 unidades
  //para que todo o intervalo tenha 30 valores (4095 / 30 = 136.5 )
  for (velocidade = 4095; velocidade >= min_vel ; velocidade = velocidade - 136.5)
  {
 
    ledcWrite(canal_vel, velocidade);//ajusta o PWM para o novo valor de velocidade
    display.clear(); //limpa o buffer do display
    display.drawString(0, 0, String(velocidade)); //escreve a velocidade no buffer
    display.display(); ///mostra no display
    delay(intervalo); //aguarda o intervalo
  }
   
  dir = !dir; //inverte a variável de controle de direção
  digitalWrite(pin_DIR, dir); // ajusta o pino de direção com o novo valor
 
  //Varia os estados do PWM do mínimo até o valor máximo em passos de 136.5 unidades
  //para que todo o intervalo tenha 30 valores (4095 / 30 = 136.5 )
  for (velocidade = min_vel; velocidade <= 4095 ; velocidade = velocidade + 136.5)
  {
    ledcWrite(canal_vel, velocidade); //ajusta o PWM para o novo valor
    display.clear();//limpa o buffer do display
    display.drawString(0, 0, String(velocidade)); //escreve a velocidade no buffer
    display.display(); //mostra no display
    delay(intervalo); //aguarda o intevalo
  }
}

Step 13: Files

Download the files

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