ESP32 Arduino code isn't responding to commands given in serial monitor

Question

I am currently working on a project with acoustic levitation arrays in the application of haptic feedback, however, the code that's provided by the original creator isn't working. The problem is that when I'm sending commands (e.g. on, off, focus, mod) through the serial monitor, nothing actually happens and the code just returns the string "yeah, I am still alive".

I have gone through the code several times now, I am aware that the creator intended for HTTP commands, however, I don't see how the same commands can't be sent through the serial monitor.

Project Link: https://www.instructables.com/SonicSurface-Phased-array-for-Levitation-Mid-air-T/

#include "WiFi.h"


#define ULTRATACT_VERSION "2.1"
const char* ssid = "UltraTactile Master";
const char* ssidMaster = "UltraTactile Master";
const char* password = "12345678";
#define BUTTON_PIN 12
#define MOD_PERIODS_DEFAULT 10

WiFiServer server(80);

#define N_TRANS 256
const float TRANS_POS[N_TRANS*3] = { -0.078749985, 0.0, 0.07874999, -0.05774999, 0.0, 0.07874999, -0.04724999, 0.0, 0.07874999, -0.068249986, 0.0, 0.06824999, -0.078749985, 0.0, 0.06824999, -0.04724999, 0.0, 0.06824999, -0.05774999, 0.0, 0.06824999, -0.068249986, 0.0, 0.07874999, -0.078749985, 0.0, 0.057749998, -0.05774999, 0.0, 0.057749998, -0.04724999, 0.0, 0.057749998, -0.068249986, 0.0, 0.04725, -0.078749985, 0.0, 0.04725, -0.04724999, 0.0, 0.04725, -0.05774999, 0.0, 0.04725, -0.068249986, 0.0, 0.057749998, -0.078749985, 0.0, 0.036750004, -0.05774999, 0.0, 0.036750004, -0.04724999, 0.0, 0.036750004, -0.068249986, 0.0, 0.026250003, -0.078749985, 0.0, 0.026250003, -0.04724999, 0.0, 0.026250003, -0.05774999, 0.0, 0.026250003, -0.068249986, 0.0, 0.036750004, -0.078749985, 0.0, 0.015750004, -0.05774999, 0.0, 0.015750004, -0.04724999, 0.0, 0.015750004, -0.068249986, 0.0, 0.0052500046, -0.078749985, 0.0, 0.0052500046, -0.04724999, 0.0, 0.0052500046, -0.05774999, 0.0, 0.0052500046, -0.068249986, 0.0, 0.015750004, -0.078749985, 0.0, -0.005249995, -0.05774999, 0.0, -0.005249995, -0.04724999, 0.0, -0.005249995, -0.068249986, 0.0, -0.015749995, -0.078749985, 0.0, -0.015749995, -0.04724999, 0.0, -0.015749995, -0.05774999, 0.0, -0.015749995, -0.068249986, 0.0, -0.005249995, -0.078749985, 0.0, -0.026249994, -0.05774999, 0.0, -0.026249994, -0.04724999, 0.0, -0.026249994, -0.068249986, 0.0, -0.036749996, -0.078749985, 0.0, -0.036749996, -0.04724999, 0.0, -0.036749996, -0.05774999, 0.0, -0.036749996, -0.068249986, 0.0, -0.026249994, -0.078749985, 0.0, -0.04724999, -0.05774999, 0.0, -0.04724999, -0.04724999, 0.0, -0.04724999, -0.068249986, 0.0, -0.05774999, -0.078749985, 0.0, -0.05774999, -0.04724999, 0.0, -0.05774999, -0.05774999, 0.0, -0.05774999, -0.068249986, 0.0, -0.04724999, -0.078749985, 0.0, -0.068249986, -0.05774999, 0.0, -0.068249986, -0.04724999, 0.0, -0.068249986, -0.068249986, 0.0, -0.078749985, -0.078749985, 0.0, -0.078749985, -0.04724999, 0.0, -0.078749985, -0.05774999, 0.0, -0.078749985, -0.068249986, 0.0, -0.068249986, -0.036749996, 0.0, 0.07874999, -0.015749995, 0.0, 0.07874999, -0.005249995, 0.0, 0.07874999, -0.026249994, 0.0, 0.06824999, -0.036749996, 0.0, 0.06824999, -0.005249995, 0.0, 0.06824999, -0.015749995, 0.0, 0.06824999, -0.026249994, 0.0, 0.07874999, -0.036749996, 0.0, 0.057749998, -0.015749995, 0.0, 0.057749998, -0.005249995, 0.0, 0.057749998, -0.026249994, 0.0, 0.04725, -0.036749996, 0.0, 0.04725, -0.005249995, 0.0, 0.04725, -0.015749995, 0.0, 0.04725, -0.026249994, 0.0, 0.057749998, -0.036749996, 0.0, 0.036750004, -0.015749995, 0.0, 0.036750004, -0.005249995, 0.0, 0.036750004, -0.026249994, 0.0, 0.026250003, -0.036749996, 0.0, 0.026250003, -0.005249995, 0.0, 0.026250003, -0.015749995, 0.0, 0.026250003, -0.026249994, 0.0, 0.036750004, -0.036749996, 0.0, 0.015750004, -0.015749995, 0.0, 0.015750004, -0.005249995, 0.0, 0.015750004, -0.026249994, 0.0, 0.0052500046, -0.036749996, 0.0, 0.0052500046, -0.005249995, 0.0, 0.0052500046, -0.015749995, 0.0, 0.0052500046, -0.026249994, 0.0, 0.015750004, -0.036749996, 0.0, -0.005249995, -0.015749995, 0.0, -0.005249995, -0.005249995, 0.0, -0.005249995, -0.026249994, 0.0, -0.015749995, -0.036749996, 0.0, -0.015749995, -0.005249995, 0.0, -0.015749995, -0.015749995, 0.0, -0.015749995, -0.026249994, 0.0, -0.005249995, -0.036749996, 0.0, -0.026249994, -0.015749995, 0.0, -0.026249994, -0.005249995, 0.0, -0.026249994, -0.026249994, 0.0, -0.036749996, -0.036749996, 0.0, -0.036749996, -0.005249995, 0.0, -0.036749996, -0.015749995, 0.0, -0.036749996, -0.026249994, 0.0, -0.026249994, -0.036749996, 0.0, -0.04724999, -0.015749995, 0.0, -0.04724999, -0.005249995, 0.0, -0.04724999, -0.026249994, 0.0, -0.05774999, -0.036749996, 0.0, -0.05774999, -0.005249995, 0.0, -0.05774999, -0.015749995, 0.0, -0.05774999, -0.026249994, 0.0, -0.04724999, -0.036749996, 0.0, -0.068249986, -0.015749995, 0.0, -0.068249986, -0.005249995, 0.0, -0.068249986, -0.026249994, 0.0, -0.078749985, -0.036749996, 0.0, -0.078749985, -0.005249995, 0.0, -0.078749985, -0.015749995, 0.0, -0.078749985, -0.026249994, 0.0, -0.068249986, 0.0052500046, 0.0, 0.07874999, 0.026250003, 0.0, 0.07874999, 0.036750004, 0.0, 0.07874999, 0.015750004, 0.0, 0.06824999, 0.0052500046, 0.0, 0.06824999, 0.036750004, 0.0, 0.06824999, 0.026250003, 0.0, 0.06824999, 0.015750004, 0.0, 0.07874999, 0.0052500046, 0.0, 0.057749998, 0.026250003, 0.0, 0.057749998, 0.036750004, 0.0, 0.057749998, 0.015750004, 0.0, 0.04725, 0.0052500046, 0.0, 0.04725, 0.036750004, 0.0, 0.04725, 0.026250003, 0.0, 0.04725, 0.015750004, 0.0, 0.057749998, 0.0052500046, 0.0, 0.036750004, 0.026250003, 0.0, 0.036750004, 0.036750004, 0.0, 0.036750004, 0.015750004, 0.0, 0.026250003, 0.0052500046, 0.0, 0.026250003, 0.036750004, 0.0, 0.026250003, 0.026250003, 0.0, 0.026250003, 0.015750004, 0.0, 0.036750004, 0.0052500046, 0.0, 0.015750004, 0.026250003, 0.0, 0.015750004, 0.036750004, 0.0, 0.015750004, 0.015750004, 0.0, 0.0052500046, 0.0052500046, 0.0, 0.0052500046, 0.036750004, 0.0, 0.0052500046, 0.026250003, 0.0, 0.0052500046, 0.015750004, 0.0, 0.015750004, 0.0052500046, 0.0, -0.005249995, 0.026250003, 0.0, -0.005249995, 0.036750004, 0.0, -0.005249995, 0.015750004, 0.0, -0.015749995, 0.0052500046, 0.0, -0.015749995, 0.036750004, 0.0, -0.015749995, 0.026250003, 0.0, -0.015749995, 0.015750004, 0.0, -0.005249995, 0.0052500046, 0.0, -0.026249994, 0.026250003, 0.0, -0.026249994, 0.036750004, 0.0, -0.026249994, 0.015750004, 0.0, -0.036749996, 0.0052500046, 0.0, -0.036749996, 0.036750004, 0.0, -0.036749996, 0.026250003, 0.0, -0.036749996, 0.015750004, 0.0, -0.026249994, 0.0052500046, 0.0, -0.04724999, 0.026250003, 0.0, -0.04724999, 0.036750004, 0.0, -0.04724999, 0.015750004, 0.0, -0.05774999, 0.0052500046, 0.0, -0.05774999, 0.036750004, 0.0, -0.05774999, 0.026250003, 0.0, -0.05774999, 0.015750004, 0.0, -0.04724999, 0.0052500046, 0.0, -0.068249986, 0.026250003, 0.0, -0.068249986, 0.036750004, 0.0, -0.068249986, 0.015750004, 0.0, -0.078749985, 0.0052500046, 0.0, -0.078749985, 0.036750004, 0.0, -0.078749985, 0.026250003, 0.0, -0.078749985, 0.015750004, 0.0, -0.068249986, 0.04725, 0.0, 0.07874999, 0.06824999, 0.0, 0.07874999, 0.07874999, 0.0, 0.07874999, 0.057749998, 0.0, 0.06824999, 0.04725, 0.0, 0.06824999, 0.07874999, 0.0, 0.06824999, 0.06824999, 0.0, 0.06824999, 0.057749998, 0.0, 0.07874999, 0.04725, 0.0, 0.057749998, 0.06824999, 0.0, 0.057749998, 0.07874999, 0.0, 0.057749998, 0.057749998, 0.0, 0.04725, 0.04725, 0.0, 0.04725, 0.07874999, 0.0, 0.04725, 0.06824999, 0.0, 0.04725, 0.057749998, 0.0, 0.057749998, 0.04725, 0.0, 0.036750004, 0.06824999, 0.0, 0.036750004, 0.07874999, 0.0, 0.036750004, 0.057749998, 0.0, 0.026250003, 0.04725, 0.0, 0.026250003, 0.07874999, 0.0, 0.026250003, 0.06824999, 0.0, 0.026250003, 0.057749998, 0.0, 0.036750004, 0.04725, 0.0, 0.015750004, 0.06824999, 0.0, 0.015750004, 0.07874999, 0.0, 0.015750004, 0.057749998, 0.0, 0.0052500046, 0.04725, 0.0, 0.0052500046, 0.07874999, 0.0, 0.0052500046, 0.06824999, 0.0, 0.0052500046, 0.057749998, 0.0, 0.015750004, 0.04725, 0.0, -0.005249995, 0.06824999, 0.0, -0.005249995, 0.07874999, 0.0, -0.005249995, 0.057749998, 0.0, -0.015749995, 0.04725, 0.0, -0.015749995, 0.07874999, 0.0, -0.015749995, 0.06824999, 0.0, -0.015749995, 0.057749998, 0.0, -0.005249995, 0.04725, 0.0, -0.026249994, 0.06824999, 0.0, -0.026249994, 0.07874999, 0.0, -0.026249994, 0.057749998, 0.0, -0.036749996, 0.04725, 0.0, -0.036749996, 0.07874999, 0.0, -0.036749996, 0.06824999, 0.0, -0.036749996, 0.057749998, 0.0, -0.026249994, 0.04725, 0.0, -0.04724999, 0.06824999, 0.0, -0.04724999, 0.07874999, 0.0, -0.04724999, 0.057749998, 0.0, -0.05774999, 0.04725, 0.0, -0.05774999, 0.07874999, 0.0, -0.05774999, 0.06824999, 0.0, -0.05774999, 0.057749998, 0.0, -0.04724999, 0.04725, 0.0, -0.068249986, 0.06824999, 0.0, -0.068249986, 0.07874999, 0.0, -0.068249986, 0.057749998, 0.0, -0.078749985, 0.04725, 0.0, -0.078749985, 0.07874999, 0.0, -0.078749985, 0.06824999, 0.0, -0.078749985, 0.057749998, 0.0, -0.068249986};
const byte PHASES_FOR_LINE[N_TRANS] = {14,6,20,15,3,10,27,24,20,14,29,22,4,14,31,5,16,14,28,14,25,6,26,4,0,2,14,25,3,18,7,21,3,7,18,21,0,14,2,25,25,26,6,4,16,28,14,14,4,31,14,5,20,29,14,22,3,27,10,24,14,20,6,15,31,0,2,28,21,25,22,3,9,11,14,3,26,0,29,17,9,12,15,29,20,26,23,18,27,31,2,9,31,6,3,5,31,3,6,5,27,2,31,9,20,23,26,18,9,15,12,29,26,29,0,17,9,14,11,3,21,22,25,3,31,2,0,28,3,9,0,5,25,22,31,14,14,19,10,11,0,27,5,25,15,19,10,5,26,21,31,26,2,6,29,17,6,0,10,13,6,10,0,13,2,29,6,17,26,31,21,26,15,10,19,5,0,5,27,25,14,10,19,11,25,31,22,14,3,0,9,5,21,3,17,8,11,5,24,17,0,10,22,11,19,5,26,27,4,6,17,3,16,27,16,25,25,23,2,14,29,5,26,10,29,26,5,10,25,2,23,14,16,16,27,25,4,17,6,3,19,26,5,27,0,22,10,11,11,24,5,17,21,17,3,8};

byte bufferToSend[N_TRANS + 2];

unsigned long millisFromLastButtonPress = 0;
byte buttonPresses = 0;

/* Array control functions */

void swichOffArray() {
  bufferToSend[0] = 254; //start phases command
  bufferToSend[N_TRANS + 1] = 253; //swap double buffer command (like a commit)
  for (int i = 1; i < N_TRANS + 1; i += 1)
    bufferToSend[i] = 32; //32 is the value for switching of the transducer
  Serial2.write( bufferToSend, N_TRANS + 2 );
  Serial2.flush();
}

void changeModulation(byte periods){
  if (periods < 1) periods = 1;
  else if(periods > 31) periods = 31;
  Serial2.write( 0b10100000 | periods);
}

const float WAVELENGTH = 0.00865f;
const float PHASE_DIV = 32.0f;
void focusArrayAt(const float posX, const float posY, const float posZ) { //positions are in meters in respect to the center of the array
  bufferToSend[0] = 254; //start phases command
  bufferToSend[N_TRANS + 1] = 253; //swap double buffer command (i.e. commit)
  for (int i = 1; i < N_TRANS+1; i += 1) {
    const float diffX = TRANS_POS[(i-1)*3 + 0] - posX;
    const float diffY = TRANS_POS[(i-1)*3 + 1] - posY;
    const float diffZ = TRANS_POS[(i-1)*3 + 2] - posZ;
    const float distInWavelengths = sqrt(diffX * diffX + diffY * diffY + diffZ * diffZ) / WAVELENGTH;
    const byte phase = (byte)((ceil(distInWavelengths) - distInWavelengths) * PHASE_DIV);
    bufferToSend[i] = phase;
  }
  Serial2.write( bufferToSend, N_TRANS + 2 );
  Serial2.flush();
}

void makeBeeps(int nBeeps, int modulation=7){
  if (nBeeps < 1) nBeeps = 1;
  else if(nBeeps > 10) nBeeps = 10;
  
  swichOffArray();
  changeModulation( modulation );
  for (int i = 0; i < nBeeps; i+=1 ){
    focusArrayAt(0,0.1,0);
    delay(250);
    swichOffArray();
    delay(250);
  }
  changeModulation( MOD_PERIODS_DEFAULT );
}




void sendPhasePattern(const byte* pattern){
  Serial2.write( 254 );
  Serial2.write( pattern, N_TRANS);
  Serial2.write( 253 );
  Serial2.flush();
}

/* Network functions*/

void configWifiAsAccessPoint(const char* ssidName){
  Serial.println("Configuring as access point...");
  WiFi.mode(WIFI_AP);
  WiFi.softAP( ssidName, password );
  Serial.println("Wait 100 ms for AP_START...");
  delay(100);
  
  Serial.println("Set softAPConfig");
  IPAddress Ip(192, 168, 1, 1);
  IPAddress NMask(255, 255, 255, 0);
  WiFi.softAPConfig(Ip, Ip, NMask);
  IPAddress myIP = WiFi.softAPIP();
  Serial.print("AP IP address: ");
  Serial.println(myIP);
}

boolean configWifiAsSlave(const byte lastIPDigit){
  Serial.println("Configuring as station...");
  WiFi.mode(WIFI_STA); 

  IPAddress local_IP(192, 168, 1, lastIPDigit);
  IPAddress gateway(192, 168, 1, 1);
  IPAddress subnet(255, 255, 255, 0);
  IPAddress primaryDNS(8, 8, 8, 8);   //optional
  IPAddress secondaryDNS(8, 8, 4, 4); //optional

  if (!WiFi.config(local_IP, gateway, subnet, primaryDNS, secondaryDNS)) {
    Serial.println("STA Failed to configure");
  }

  Serial.println("Conecting to master");
  WiFi.begin(ssidMaster, password); 
  for (int tries = 0; WiFi.status() != WL_CONNECTED; tries+= 1) { 
    delay(250); 
    Serial.print("."); 
    if (tries >= 4*5){ //after 5 seconds trying to connect
       Serial.println("failure connecting to the master SSID");
       return false;
    }
  } 
  
  IPAddress myIP = WiFi.localIP();
  Serial.print("Station IP address: ");
  Serial.println(myIP);
  return true;
}

void setup() {
  Serial.begin(115200); // this serial is for receiving commands and sending debug info to the computer
  Serial2.begin(115200 , SERIAL_8N1, 17, 16); //RX2 TX2 This serial communicates with the array
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  Serial.println(ULTRATACT_VERSION);
  Serial.println( ssid );

  configWifiAsAccessPoint( ssid ); //start as access point with regular ssid  
  server.begin();
  delay(200);
  Serial.println("Switching off the array...");

  makeBeeps( 1 );
}




int previousButton = HIGH;
int itersButtonHigh = 0;
bool randomMode = false;
unsigned long randomModeTriggerMillis = 0;

void loop() {  
  const unsigned long currentMillis = millis();

  /* Button pres input */
  if ( currentMillis - millisFromLastButtonPress > 1000 && buttonPresses > 0){
    randomMode = false;
    swichOffArray();
    if (buttonPresses == 1){ //switch off the emitter
      Serial.println("Button pressed once, switching off the array");
    }else if (buttonPresses >= 2){ //try to connect to the master ssid, 
      const int lastIPDigit = 98 + buttonPresses; //with increasing IP numbers (.101 .102 ...)
      Serial.print("Button pressed >=2, connecting with ip ");
      Serial.println(lastIPDigit);
      const boolean conectedToMaster = configWifiAsSlave(lastIPDigit);
      if (conectedToMaster == false ){ //we failed connecting to the master, so we become the master
        configWifiAsAccessPoint(ssidMaster);
        makeBeeps( 1, 5 );
      }else{
        makeBeeps( buttonPresses );
      }
    }
    delay(500);
    buttonPresses = 0;
  }
  
  const int currentButtonState = digitalRead(BUTTON_PIN);
  if (previousButton == HIGH && currentButtonState == LOW && itersButtonHigh > 100){ //when the button is pressed. last part is for avoid bouncing
    buttonPresses += 1;
    millisFromLastButtonPress = currentMillis;
  }
  if ( currentButtonState == HIGH && itersButtonHigh < 0x0FFF){
    itersButtonHigh += 1;
  }else{
    itersButtonHigh = 0;
  }
  previousButton = currentButtonState;


  /* Serial control, mainly to debug*/
if (Serial.available() > 1) {
      byte letter = Serial.read();
      Serial.read(); //read the newline
      if (letter == 's') {
        swichOffArray();
      } else if (letter == 'f') {
        focusArrayAt( 0, 0.1f, 0);
      } else {
        Serial.println("Yeah, I am still alive");
      }
    }

  /* random mode*/
  if (randomMode && randomModeTriggerMillis <= currentMillis){
    randomModeTriggerMillis = currentMillis + random(20,150);
    focusArrayAt( random(-40,40) / 1000.0f, random(90,110) / 1000.0f, random(-40,40) / 1000.0f);
  }
  
  
  /* Commands comming from HTTP */
  WiFiClient client = server.available();
  if (client) {
    String request = client.readStringUntil('\r');
    Serial.print( currentMillis );
    Serial.print(' ');
    Serial.println( request );

    client.println("HTTP/1.1 200 OK\nContent-type:text/html\nConnection: close\n\n");

    // /focus/x_y_z
    // /off
    // /mode/number  number 1 to 4, mainly affects the modulation frequency
    // /line   at 10cm, 0 degrees
    // /noise    at 10cm, sparks (random mode)
  
    int sep1 = request.indexOf('/');
    if (sep1 == -1) 
      return;

    //disable randomMode (noise pop...)
    randomMode = false;
    
    //command
    if ((sep1 = request.indexOf("focus", sep1+1)) != -1){
      const int sep2 = request.indexOf('/', sep1 + 1);
      const int sep3 = request.indexOf('_', sep2 + 1);
      const int sep4 = request.indexOf('_', sep3 + 1);
      const int sep5 = request.indexOf(' ', sep4 + 1);
      if (sep2 == -1 || sep3 == -1 || sep4 == -1 || sep5 == -1)
        return;
  
      const float posX = request.substring(sep2 + 1, sep3).toFloat();
      const float posY = request.substring(sep3 + 1, sep4).toFloat();
      const float posZ = request.substring(sep4 + 1, sep5).toFloat();
      Serial.printf("Focusing at %f %f %f\n", posX, posY, posZ);
      focusArrayAt( -posX, posY, posZ);
      Serial.println("Focused");
      client.printf("Focused at %f %f %f\n", posX, posY, posZ);
      
    }else if((sep1 = request.indexOf("off", sep1+1)) != -1){
      Serial.println("Switching off the array...");
      swichOffArray();
    }else if((sep1 = request.indexOf("mode", sep1+1)) != -1){
      const int sep2 = request.indexOf('/', sep1 + 1);
      const int sep3 = request.indexOf(' ', sep2 + 1);
      const int mod = request.substring(sep2 + 1, sep3).toInt();
      
      if (mod == 1){
        changeModulation( MOD_PERIODS_DEFAULT );
      }else if (mod == 2){
        changeModulation( 7 );
      }else if (mod == 3){
        changeModulation( 15 );
      }else if (mod == 4){
       changeModulation( 8 );
      }else{
        changeModulation( MOD_PERIODS_DEFAULT );
      }
 
    }else if((sep1 = request.indexOf("line", sep1+1)) != -1){
      Serial.println("Emitting a line...");
      sendPhasePattern( PHASES_FOR_LINE );
    }else if((sep1 = request.indexOf("sparks", sep1+1)) != -1){
      Serial.println("Emitting noise...");
      randomMode = true;
      randomModeTriggerMillis = currentMillis;
    }else if((sep1 = request.indexOf("version", sep1+1)) != -1){
      Serial.println("Version is");
      client.printf("Version is %s\n", ULTRATACT_VERSION);
    }

    client.stop();
  }

}```