ESP32: Laboratorios

ESP32: Laboratórios

A placa Heltec ESP32 LoRa é uma placa de desenvolvimento que integra três formas distintas de comunicação: Wifi, Bluetooth e a rede de comunicação de longo alcance LoRa. Além disto a placa apresenta um display OLED, o que facilita o controle da operação do dispositivo localizado em locais remotos.

Instalação da placa do Heltec ESP32 com a IDE do Arduino

1. IDE -> Arquivo -> Preferências
2. URLs Adicionais para Gerenciadores de Placa: https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json, https://github.com/Heltec-Aaron-Lee/WiFi_Kit_series/releases/download/0.0.5/package_heltec_esp32_index.json
3. Ferramentas -> Gerenciadores de Placa -> Instalar Heltec ESP32 Series Dev/boards
4. Selecionar placa WiFi LoRa 32

Laboratório 1: Wifi

Exemplo pronto da biblioteca padrão do Arduino: Arquivo -> Exemplos -> Wifi -> SimpleWifiServer:

• Configurar apenas ssid e passwd da rede Wifi;
• Identificar via terminal serial o endereço IP recebido pelo ESP32;
• Será possível controlar led (gpio 5, ou outro) via nagerador Web.

Laboratório 2: Bluetooth

Exemplo pronto da biblioteca padrão do Arduino: Arquivo -> Exemplos -> BluetoothSerial -> SerialToSerialBT:

Exemplo de interação bluetooth entre ESP32 e Android Serial Bluetooth Terminal.

• Carregar código no ESP32;
• Instalar aplicativo Serial Bluetooth Terminal no Android;
• Parear o ESP32 com o Android;
• Trocar mensagens seriais entre o terminal do ESP32 e o aplicativo Serial Bluetooth Terminal

Laboratório 3: Bluetooth Low Energy - BLE

Ver detalhes do BLE: https://randomnerdtutorials.com/esp32-bluetooth-low-energy-ble-arduino-ide/.

Biblioteca: https://github.com/nkolban/ESP32_BLE_Arduino

• Exemplo pronto Arquivo -> Exemplos -> ESP BLE Arduino -> BLEserver;
• Instalar aplicativo BLE Terminal no Android;
• Conectar ao dispositivo.

Laboratório 4: Servidor Web e Display OLED

Exemplo de Web Server construído a partir de dois exemplos prontos:

• Wifi: busca de redes e conexão baseadas no exemplo:

Arquivo -> Exemplos -> Heltec ESP Dev-Boards -> Factory_Tests -> WIFI_Kit_32_Factory_Test

• Servidor Web: baseado no exemplo:

Arquivo -> Exemplos -> Wifi -> SimpleWiFiServer

Código

/*
 * Web Server
 * 
 * Wifi: busca de redes e conexão baseadas no exemplo:
 * Arquivo -> Exemplos -> Heltec ESP Dev-Boards -> Factory_Tests -> WIFI_Kit_32_Factory_Test
 * 
 * Servidor Web: baseado no exemplo:
 * Arquivo -> Exemplos -> Wifi -> SimpleWiFiServer
*/

#include "heltec.h"
#include "WiFi.h"
#include "images.h"

WiFiServer server(80);

void logo(){
	Heltec.display -> clear();
	Heltec.display -> drawXbm(0,5,HelTec_LOGO_width,HelTec_LOGO_height,(const unsigned char *)HelTec_LOGO_bits);
	Heltec.display -> display();
  delay(1000);
  Heltec.display->clear();
}

void wifi_logo(){
  Heltec.display -> clear();
  Heltec.display->drawXbm(34, 19, WiFi_Logo_width, WiFi_Logo_height, WiFi_Logo_bits);
  Heltec.display -> display();
  delay(1000);
  Heltec.display->clear();
}


void WIFISetUp(void)
{
	// Set WiFi to station mode and disconnect from an AP if it was previously connected
	WiFi.disconnect(true);
	delay(1000);
	WiFi.mode(WIFI_STA);
	WiFi.setAutoConnect(true);
	WiFi.begin("SSID","passwd");
	delay(100);

	byte count = 0;
	while(WiFi.status() != WL_CONNECTED && count < 10)
	{
		count ++;
    if (count == 1) Serial.println("Connecting...");
		delay(500);
    Heltec.display->clear();
		Heltec.display -> drawString(0, 0, "Connecting...");
		Heltec.display -> display();
	}

	Heltec.display -> clear();
	if(WiFi.status() == WL_CONNECTED)
	{
		Heltec.display -> drawString(0, 0, "Connecting...OK.");
		Heltec.display -> display();
		delay(500);
    Heltec.display -> drawString(0, 10, "IP address: ");
    Heltec.display -> display();
    delay(500);
    Heltec.display -> drawString(0, 20, WiFi.localIP().toString());
    Heltec.display -> display();
    delay(2000);
    Serial.println("WiFi connected");
    Serial.println("IP address: ");
    Serial.println(WiFi.localIP());
	}
	else
	{
		Heltec.display -> clear();
		Heltec.display -> drawString(0, 0, "Connecting...Failed");
		Heltec.display -> display();
    Serial.println("Connecting...Failed");
//		while(1);
	}
	Heltec.display -> drawString(0, 40, "WIFI Setup done");
	Heltec.display -> display();
  Serial.println("WIFI Setup done");
	delay(500);
  Heltec.display->clear();
}

void WIFIScan(void)
{
	Heltec.display -> drawString(0, 20, "Scan start...");
	Heltec.display -> display();
  Serial.println("Scan start...");

	int n = WiFi.scanNetworks();
	Heltec.display -> drawString(0, 30, "Scan done");
	Heltec.display -> display();
  Serial.println("Scan done");
	delay(500);
	Heltec.display -> clear();

	if (n == 0)
	{
		Heltec.display -> clear();
		Heltec.display -> drawString(0, 0, "no network found");
		Heltec.display -> display();
    Serial.println("No network found");
		while(1);
	}
	else
	{
    Serial.print(n);
		Heltec.display -> drawString(0, 0, (String)n);
		Heltec.display -> drawString(14, 0, "networks found:");
		Heltec.display -> display();
    Serial.print(n);
    Serial.println(" networks found:");
		delay(500);

		for (int i = 0; i < n; ++i) {
		// Print SSID and RSSI for each network found
			Heltec.display -> drawString(0, (i+1)*9,(String)(i + 1));
			Heltec.display -> drawString(6, (i+1)*9, ":");
			Heltec.display -> drawString(12,(i+1)*9, (String)(WiFi.SSID(i)));
			Heltec.display -> drawString(90,(i+1)*9, " (");
			Heltec.display -> drawString(98,(i+1)*9, (String)(WiFi.RSSI(i)));
			Heltec.display -> drawString(114,(i+1)*9, ")");
			//            display.println((WiFi.encryptionType(i) == WIFI_AUTH_OPEN)?" ":"*");
      Serial.print(i+1);
      Serial.print(" : ");
      Serial.print(WiFi.SSID(i));
      Serial.print(" (");
      Serial.print(WiFi.RSSI(i));
      Serial.println(")");
			delay(10);
		}
	}

	Heltec.display -> display();
	delay(800);
	Heltec.display -> clear();

}

void setup()
{
	pinMode(LED,OUTPUT);

	Heltec.begin(true /*DisplayEnable Enable*/, false /*LoRa Enable*/, true /*Serial Enable*/);

	logo();
  wifi_logo();
  WIFIScan();
	WIFISetUp();
    
  //WiFi.disconnect(true);//重新初始化WIFI
  //delay(1000);
  //WiFi.mode(WIFI_STA);
  //WiFi.setAutoConnect(true);

  server.begin();
  Heltec.display -> drawString(0, 0, "Waiting Web Clients");
  Heltec.display -> display();

}

void loop(){
 WiFiClient client = server.available();   // listen for incoming clients

  if (client) {                             // if you get a client,
    Serial.println("New Client.");           // print a message out the serial port
    Heltec.display -> clear();
    Heltec.display -> drawString(0, 0, "New Web Client");
    Heltec.display -> display();
    String currentLine = "";                // make a String to hold incoming data from the client
    while (client.connected()) {            // loop while the client's connected
      if (client.available()) {             // if there's bytes to read from the client,
        char c = client.read();             // read a byte, then
        Serial.write(c);                    // print it out the serial monitor
        if (c == '\n') {                    // if the byte is a newline character

          // if the current line is blank, you got two newline characters in a row.
          // that's the end of the client HTTP request, so send a response:
          if (currentLine.length() == 0) {
            // HTTP headers always start with a response code (e.g. HTTP/1.1 200 OK)
            // and a content-type so the client knows what's coming, then a blank line:
            client.println("HTTP/1.1 200 OK");
            client.println("Content-type:text/html");
            client.println();
            // the content of the HTTP response follows the header:
            client.print("Click <a href=\"/H\">here</a> to turn the LED on.<br>");
            client.print("Click <a href=\"/L\">here</a> to turn the LED off.<br>");

            // The HTTP response ends with another blank line:
            client.println();
            // break out of the while loop:
            break;
          } else {    // if you got a newline, then clear currentLine:
            currentLine = "";
          }
        } else if (c != '\r') {  // if you got anything else but a carriage return character,
          currentLine += c;      // add it to the end of the currentLine
        }

        // Check to see if the client request was "GET /H" or "GET /L":
        if (currentLine.endsWith("GET /H")) {
          digitalWrite(LED, HIGH);               // GET /H turns the LED on
          Heltec.display -> drawString(0, 10, "Turn LED on");
          Heltec.display -> display();
        }
        if (currentLine.endsWith("GET /L")) {
          digitalWrite(LED, LOW);                // GET /L turns the LED off
          Heltec.display -> drawString(0, 10, "Turn LED off");
          Heltec.display -> display();
          
        }
      }
    }
    // close the connection:
    client.stop();
    Serial.println("Client Disconnected.");
  }
}

Laboratório 5: LoRa Emissor e Receptor

Exemplo de comunicação LoRa baseado em dois exemplos prontos:

Arquivo -> Exemplos -> Heltec ESP Dev-Boards -> LoRa -> LoraSender
Arquivo -> Exemplos -> Heltec ESP Dev-Boards -> LoRa -> LoraReceiver

Aos exemplos prontos foi acrescentada a biblioteca images.h para mostrar a comunicação no Display OLED.

Antenas: Para que a comunicação LoRa ocorra deve-se conectar as antenas em cada módulo.

Emissor LoRa

/* 
  Basic test program, send date with LoRa.
  https://github.com/Heltec-Aaron-Lee/WiFi_Kit_series
*/
#include "heltec.h"
#define BAND    433E6  //you can set band here directly,e.g. 868E6,915E6
#include "images.h"

void lora(){
  Heltec.display -> clear();
  Heltec.display -> drawXbm(34, 19, LoRa_Logo_width, LoRa_Logo_height, LoRa_Logo_bits);
  Heltec.display -> display();
  delay(2000);
  Heltec.display->clear();
}

int counter = 0;

void setup() {
  
  //WIFI Kit series V1 not support Vext control
  Heltec.begin(true /*DisplayEnable Enable*/, true /*Heltec.LoRa Disable*/, true /*Serial Enable*/, true /*PABOOST Enable*/, BAND /*long BAND*/);
  lora();
  LoRa.setSyncWord(0xF3);
}

void loop() {
  Serial.print("Sending packet: ");
  Serial.println(counter);
  Heltec.display -> clear(); 
  Heltec.display -> drawString(0, 0, "Sending packet: ");
  Heltec.display -> drawString(0, 10,(String)(counter));
  Heltec.display -> display();
  // send packet
  
  LoRa.beginPacket();
/*
* LoRa.setTxPower(txPower,RFOUT_pin);
* txPower -- 0 ~ 20
* RFOUT_pin could be RF_PACONFIG_PASELECT_PABOOST or RF_PACONFIG_PASELECT_RFO
*   - RF_PACONFIG_PASELECT_PABOOST -- LoRa single output via PABOOST, maximum output 20dBm
*   - RF_PACONFIG_PASELECT_RFO     -- LoRa single output via RFO_HF / RFO_LF, maximum output 14dBm
*/
  LoRa.setTxPower(20,RF_PACONFIG_PASELECT_PABOOST);
  LoRa.print("hello ");
  LoRa.print(counter);
  LoRa.endPacket();
  
  counter++;
  digitalWrite(25, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);                       // wait for a second
  digitalWrite(25, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);                       // wait for a second
}

Receptor LoRa

/* 
  Check the new incoming messages, and print via serialin 115200 baud rate.
  https://github.com/Heltec-Aaron-Lee/WiFi_Kit_series
*/

#include "heltec.h"
#include "images.h"

char message[20];

void lora(){
  Heltec.display -> clear();
  Heltec.display -> drawXbm(34, 19, LoRa_Logo_width, LoRa_Logo_height, LoRa_Logo_bits);
  Heltec.display -> display();
  delay(2000);
  Heltec.display->clear();
}

#define BAND    433E6  //you can set band here directly,e.g. 868E6,915E6
void setup() {
    //WIFI Kit series V1 not support Vext control
  Heltec.begin(true /*DisplayEnable Enable*/, true /*Heltec.LoRa Disable*/, true /*Serial Enable*/, true /*PABOOST Enable*/, BAND /*long BAND*/);
  lora();
  LoRa.setSyncWord(0xF3);
}

void loop() {
  // try to parse packet
  int packetSize = LoRa.parsePacket();
  if (packetSize) {
    // received a packet
    Serial.print("Received packet '");
    // read packet
    char c;
    int i = 0;
    while (LoRa.available()) {
      c = (char)LoRa.read();
      Serial.print(c);
      message[i] = c;
      i++;
      //sprintf(message, LoRa.read())
    }
    // print RSSI of packet
    Serial.print("' with RSSI ");
    Serial.println(LoRa.packetRssi());
   
    Heltec.display -> clear(); 
    Heltec.display -> drawString(0, 0, "Received packet: ");
    Heltec.display -> drawString(0, 10, (String)message);
    Heltec.display -> drawString(0, 20, "RSSI: ");
    Heltec.display -> drawString(0, 30, (String)LoRa.packetRssi());
    Heltec.display -> display();
    
  }
}

Laboratório 6: Sensores embutidos do ESP32

O ESP32 possui alguns sensores embutidos, como sensores de toque e sensor de efeito hall.

Sensores de toque

O ESP32 possui 10 sensores de toque (Touch Sensor). São sensores capacitivos sensíveis a pequenas cargas elétricas, como quando um dedo for tocado em um dado terminal elétrico.

A referência Introducing the ESP32 Touch Sensor detalha o funcionamento deste sensor.

Laboratório Touch Read

O exemplo da Arduino IDE: Examples -> ESP32 -> Touch -> TouchRead, ilustra o funcionamento do sensor de toque:

// ESP32 Touch Test
// Just test touch pin - Touch0 is T0 which is on GPIO 4.

void setup()
{
  Serial.begin(115200);
  delay(1000); // give me time to bring up serial monitor
  Serial.println("ESP32 Touch Test");
}

void loop()
{
  Serial.println(touchRead(T0));  // get value using T0
  delay(1000);
}

Laboratório Touch Sensitive Led

Veja na referência como controlar saídas usando sensores de toque.

Sensores de Efeito Hall

O ESP32 possui um sensor de efeito hall (Hall Sensor), que detecta variação no campo magnético nas vizinhanças do ESP32. O sensor de efeito hall está localizado junto a parte metálica que envolve o ESP32.

A referência ESP32 Built-In Hall Effect Sensor detalha o funcionamento deste sensor.

Laboratório Hall Sensor

O exemplo da Arduino IDE: Examples -> ESP32 -> HallSensor, ilustra o funcionamento do sensor:

// Simple sketch to access the internal hall effect detector on the esp32.
// values can be quite low. 
// Brian Degger / @sctv  

int val = 0;

void setup() {
  Serial.begin(9600);
}

// put your main code here, to run repeatedly
void loop() {
  // read hall effect sensor value
  val = hallRead();
  // print the results to the serial monitor
  Serial.println(val); 
  delay(1000);
}
}

void loop()
{
  Serial.println(touchRead(T0));  // get value using T0
  delay(1000);
}

Referências

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Evandro.cantu (discussão) 15h48min de 8 de fevereiro de 2022 (-03)

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