Programmation avancée

   Les bases de la programmation arduino avec esp8266/esp32

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Catégorie : Programmation avancée
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 1°/ Structuration d'un sketch (= programme)

2°/ Lire/écrire sur les pins GPIO

 

 

 

void setup() {
  pinMode(D3, OUTPUT);
  pinMode(D2, INPUT);
  ...
}

 

int val = analogRead(A0);
byte b = digitalRead(D2);
...
analogWrite(25, 1234); // write 1234 on pin 25 of an esp32, which corresponds to 3.3*1234/4096 = 0.9942V
digitalWrite(D3,HIGH); // on an esp8266, D3 now outputs 3.3V
digitalWrite(D3,LOW); // on an esp8266, D3 now outputs 0V

 

3°/ Communication série

...
void setup() {
  Serial.begin(115200); // initialize serial connection at 115200 bauds
  Serial.println("hello");
  ...
}

 

Remarques : 

 

 

4°/ Interruptions

Exemple : pin D3 d'une carte basée sur un esp8266

volatile byte state;
...
void ICACHE_RAM_ATTR mycallback() {
  state = digitalRead(D3);
  ...
}
...
void setup() {
  ...
  attachInterrupt(digitalPinToInterrupt(D3), mycallback, CHANGE);
  ...
}
Remarques: 
 
5°/ Pulse Width Modulation (PWM)

Duty Cycle Examples

 

 

 

 

Exemple sur une esp8266/arduino :

analogWriteRange(100);
analogWirteFreq(10000); // 10KHz
analogWrite(D3,13); // duty cycle = 13/range = 13/100 =>  13%

 

Remarques :

 6°/ Wifi

 


6.1°/ client Wifi

Exemple :

#include <ESP8266WiFi.h>
...
void setupWifi() {
     
  const char *ssid = "ssid_wifi_ap"; // the ssid of the AP        
  const char *password = "pass_ap"; // the password of the AP  
  
  // comment 2 following lines if not needed
  WiFi.setAutoConnect(false);  // see comments   
  ret = WiFi.setSleepMode(WIFI_NONE_SLEEP); // always active => big consumption

  ret = WiFi.mode (WIFI_STA); // setup as a wifi client
  ret = WiFi.begin(ssid,password); // try to connect
  while (WiFi.status() != WL_CONNECTED) { // check connection
    delay(500); 
    Serial.print(".");
  } 
  // debug messages
  Serial.print("Connected, IP address: ");
  Serial.println(WiFi.localIP());
}

 

Remarques : 

6.2°/ Point d'accès + client Wifi access

Apparté :

 

Exemple :

#include <ESP8266WiFi.h>
...
void setupAP() {
  IPAddress local_IP(192,168,0,1);
  IPAddress gateway(192,168,0,1);
  IPAddress subnet(255,255,255,0);

  ret = WiFi.mode(WIFI_AP_STA); // AP + client
  int channel = 1; // choose between 1 and 13
  const char *ssid = "ssid_wifi_ap";        
  const char *password = "pass_ap";  

 // CAUTION: on other µC, 2 following lines may be exchanged to work
  ret = WiFi.softAP(ssid, password, channel); 
  ret = WiFi.softAPConfig(local_IP, gateway, subnet);

  // debug messages
  IPAddress myIP = WiFi.softAPIP();
  Serial.print("AP IP address: ");
  Serial.println(myIP);
}

 

Remarques :

 

7°/ Connexion et communcation TCP

 

7.1°/ client TCP

Exemple :

#include <ESP8266WiFi.h>
...
WiFiClient client;
byte connState;
const char* ipServ = "192.168.0.1";
int portServ = 12345;
byte buf[1024];
int idx = 0;
...

void setup() {
  Serial.begin(115200);
  connState = 0;
  // establish the wifi connection
  ...
}

bool doConnection() {
  if (client.connect(ipServ, portServ)) {
    connState = 1;
    Serial.println("connected to server")
    // special for esp8266: disable buffering small mesg
    client.setNoDelay(true);
    return true;
  }
  else {
    connState = 0;
    Serial.println("connection failed")
    return false;
}

void loop() {
  if (connState == 0) {
    if (! doConnection()) { delay(1000); }
  }
  if (connState == 1) {
    client.write(10); // write a byte equal to 10
    client.println("10"); // write 3 bytes: ascii code of 1, ascii code of 0, ascii code of new_line
    // wait something from the server
    while (!client.available()) {} // see comments below
    // read what is available
    while (client.available()) {
      buf[idx++] = client.read(); // read & store a byte
    }
    Serial.println(String(buf)); // print the content of buf as a string
    for(int i=0;i<idx;i++) buf[i] = 0; // reset buf
  }
}

 

Remarques :

 

7.2°/ serveur TCP

Exemple :

#include <ESP8266WiFi.h>
...
WiFiServer server(12345);
WiFiClient client;
byte connState;
byte buf[1024];
int idx = 0;
...

void setup() {
  Serial.begin(115200);
  connState = 0;
  // establish the wifi connection
  ...
}

void waitConnection() {
  client = server.available(); // test if there is an incoming connection and if yes, accept it.
  if (client) {
    connState = 1;
    Serial.println("client connected")
    // special for esp8266: disable buffering small mesg
    client.setNoDelay(true);
  }
}

void loop() {
  if (connState == 0) {
    waitConnection();
  }
  if (connState == 1) {
    // wait something from the client
    while (!client.available()) {}
    // read what is available
    while (client.available()) {
      buf[idx++] = client.read(); // read & store a byte
    }
    Serial.println(String(buf)); // print the content of buf as a string
    for(int i=0;i<idx;i++) buf[i] = 0; // reset buf
  }
}

 

 

8°/ A propos de la consommation électrique