I am interested to use ESP-NOW as a means to transmit data between two ESP32's back and forth, - each ESP receives and sends data, taking turns. The example library provides an example sketch for Slave and one for Master, which allows for one-directional data flow. However, I would like to use ESP-NOW for two-way communication. Is it possible to combine both of these sketches to allow the data to flow in both directions at the same time?

ESP32 Library showing Slave and Master examples

I'm assuming two ESP's won't be able to send data at the same exact time, so the best approach to start, I think, would be to wait until a packet has been received before sending one from the other end. Here's a snippet of code which I tried to use, but failed:

void setup()
  // configure device AP mode
  // This is the mac address of the Slave in AP Mode
  Serial.print("AP MAC: ");
  Serial.print("STA MAC: ");
  // Init ESPNow with a fallback logic
  // Once ESPNow is successfully Init, we will register for recv CB to
  // get recv packer info.

unsigned long nextManage;

void loop() 
  // In the loop we scan for slave
  // If Slave is found, it would be populate in `slave` variable
  // We will check if `slave` is defined and then we proceed further
  if (slave.channel == CHANNEL2)
  { // check if slave channel is defined
    // `slave` is defined
    // Add slave as peer if it has not been added already
    bool isPaired = manageSlave();
    nextManage = millis() + 10000;
    while (isPaired)
      if (packetRecieved)
        packetRecieved = false;
        // Send data to device

      unsigned long t = millis();
      if (t > nextManage)
        nextManage = t + 10000;
        // pair success or already paired
        isPaired = manageSlave();
    Serial.println("Slave pair failed!");


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