Arduino Mega 2560 + ESP8266-01


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Arduino Mega 2560 + ESP8266-01
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Arduino Mega 2560 + ESP8266-01

I would like some help to connect an Arduino Mega 2560 with a ESP8266-01 linked in serial 2.

I could connect on the internet using some “AT Comands”, but I could not connect in Cayenne.

Someone could help me with this.


Follow my sketch:

* ESP8266
* Arduino Mega Using Serial2
* AT commands examples for test:
* AT =====> ESP8266 returns OK
* AT+RST =====> ESP8266 restart and returns OK
* AT+GMR =====> ESP8266 returns AT Version; SDK version; id; OK
* AT+CWMODE? => ESP8266 returns mode type
* AT+CWLAP ===> ESP8266 returs close access points
* AT+CIFSR ===> ESP8266 returs designided IP
* AT+CIPMUX=1 ==>Set ESP8266 for multoples conections 
* AT+CIOBAUD=9600 ==>Change Baudrate ==> ESP8266 returs OK
* AT+CIPSERVER=1,80 ==> set modo SERVER port: 4040
* AT+CWMODE=3 ==> Conect ESP8266 ascombined mode (Access Point (2) and Server (1))
* AT+CWSAP="Acc_Point_name","password",wifi_Channel,cript# ==> ej. AT+CWSAP="ESP_8266_AP,"1234",3,0
* AT+CWJAP="SSID","password" ==> Connect to WiFi network
* Marcelo Jose Rovai 18Jan16

#define CAYENNE_PRINT Serial  // Comment this out to disable prints and save space

#include <doxygen.h>
#include <ESP8266.h>
#define esp8266 Serial2
#define CH_PD 4 
#define speed8266 19200 // This is the speed that worked with my ESP8266
//Coloque nos campos indicados o nome e senha da sua rede WiFi
#define SSID        "Vick Cristina Barcelona"
#define PASSWORD    "rafa0402"

// Token de Autenticação do Cayenne Mydevices
char token[] = "27hmhv6grc";
//Cria objeto de conexão wifi com o módulo, usando a Serial1 do Mega.
ESP8266 wifi(Serial2);
void setup(void)
digitalWrite(CH_PD,HIGH); //setado em ALTO - operacao normal

esp8266.begin (speed8266); 
//reset8266(); // Pin CH_PD need a reset before start communication

Serial.println("Iniciando Setup.");

Serial.print("Versao de Firmware ESP8266: ");
//A funcao wifi.getVersion() retorna a versao de firmware informada pelo modulo no inicio da comunicacao
//Vamos setar o modulo para operar em modo Station (conecta em WiFi) e modo AP (é um ponto de WiFi tambem)
if (wifi.setOprToStationSoftAP()) {
    Serial.println("Station e AP OK.");
} else {
    Serial.println("Erro em setar Station e AP.");
//Agora vamos conectar no ponto de WiFi informado no inicio do codigo, e ver se corre tudo certo
if (wifi.joinAP(SSID, PASSWORD)) {
    Serial.println("Conectado com Sucesso.");
    Serial.println("IP: ");
    //rotina wifi.getLocalIP() retorna o IP usado na conexao com AP conectada.
} else {
    Serial.println("Falha na conexao AP.");

//Agora vamos habiliar a funcionalidade MUX, que permite a realizacao de varias conexoes TCP/UDP
if (wifi.enableMUX()) {
    Serial.println("Multiplas conexoes OK.");
} else {
    Serial.println("Erro ao setar multiplas conexoes.");

//Inicia servidor TCP na porta 8090 (veja depois a funcao "startServer(numero_porta)", que serve para UDP!
if (wifi.startTCPServer(8090)) {
    Serial.println("Servidor iniciado com sucesso.");
} else {
    Serial.println("Erro ao iniciar servidor.");
Serial.println("Setup finalizado!");

  //  Cayenne.begin(token, ssid, password);
  //  Cayenne.config(token); //If this doesn't work, try Blynk.config(token);

//Na conexao TCP, basicamente a funcionalidade a ser mostrada sera a de "echo", ou seja, a aplicacao ira retornar todos os //dados enviados para ela via socket TCP.
void loop(void)
//Variavel para buffer de dados de trasmissao
uint8_t buffer[128] = {0};
//Como usamos multiplas conexoes, cada conexao tem sua ID, e precisa ser armazenada para referencia no programa. Usamos    //essa variavel para isso.
uint8_t mux_id;
//E esta variavel len serve para armazenar o comprimento de dados recebidos por meio da rotina wifi.recv(), que tambem     //associa ao buffer os dados recebidos e ao mux_id a id responsavel pela transmissao
uint32_t len = wifi.recv(&mux_id, buffer, sizeof(buffer), 100);
if (len > 0) {
    Serial.print("Recebido de :");
    for(uint32_t i = 0; i < len; i++) {
    //Agora envia de volta. A referencia para o socket TCP criado é o mux_id, ou id da conexao, usado aqui na rotina
    //wifi.send, veja abaixo:
    if(wifi.send(mux_id, buffer, len)) {
        Serial.print("Enviado de volta...\r\n");
    } else {
        Serial.print("Erro ao enviar de volta\r\n");
    //E, como sempre, liberar a conexao TCP, de modo a permitir que novas conexoes sejam realizadas.
    if (wifi.releaseTCP(mux_id)) {
        Serial.print("Liberando conexao TCP com ID: ");
        Serial.println(" OK");
    } else {
        Serial.print("Erro ao liberar TCP com ID: ");


// Reset funtion to accept communication
void reset8266 ()
 pinMode(CH_PD, OUTPUT);
 digitalWrite(CH_PD, LOW);
 digitalWrite(CH_PD, HIGH);


Give this post a try and see if it gets you connected WifiShield with arduino uno compiling error


Tks Adam.

I performed the code but I could not conect in cayenne:

[519] Connecting to Vick Cristina Barcelona
[5610] IP: +CIFSR:STAIP,“”

[6635] Failed to disable MUX
[6635] Connected to WiFi

but in cayenne dashboard I could not connect.


@kreggly any ideas? I suppose at some point I should get an ESP out and try this out myself.


Don’t know.

I have an ESP-02 board to work with now, but not an ESP-01.

Don’t know if anyone has actually got an ESP-01 connected to Cayenne with the serial commands. Might be an incompatibility. We know the ESP-07 and ESP-12 ones work fine.




I do have a 1 around here somewhere. I’ll give it a try when I get a chance.


Thank you in advance.

I´m using something like this

The only difference is that instead of the resistors I am using a CD4050 module to guarantee the 3.3V to the ESP.


@adam Could you have a chance to try this device. Tks


Yep, worked fine for me. WifiShield with arduino uno compiling error