ESP8266 Community Forum

- Thu Apr 22, 2021 6:26 am #91168 Hello,

I configured 2 ESP-12E cards with ESPNOW protocol.

My first attempts were successful. But for no apparent reason I now have a messaging problem.

When I plug in my sender board: Delivery success
When I press the reset button on sender board: Delivery fail

Why do I now have a failure with the reset button?

Sender code

Code: Select all#include <espnow.h>

// Set your Board ID (ESP8266 Sender #1 = BOARD_ID 1, ESP8266 Sender #2 = BOARD_ID 2, etc)
#define BOARD_ID 1

//MAC Address of the receiver -- ESP-12E
uint8_t broadcastAddress[] = {0x99, 0x99, 0x99, 0x99, 0x99, 0x99};

//Structure example to send data
//Must match the receiver structure
typedef struct struct_message {
    int topic;
    char payload[2];
} struct_message;

//Create a struct_message called myData
struct_message myData;


// Callback when data is sent
void OnDataSent(uint8_t *mac_addr, uint8_t sendStatus) {
  Serial.print("Last Packet Send Status: ");
  if (sendStatus == 0){
    Serial.println("Delivery success\n");
  }
  else{
    Serial.println("Delivery fail\n" + String(sendStatus));
  }
}


void setup() {

  //Init Serial Monitor
  Serial.begin(9600);
  delay(10);

  // Init ESP-NOW
  if (esp_now_init() != 0) {
    Serial.println("Error initializing ESP-NOW");
    return;
  }
 
  // Once ESPNow is successfully Init, we will register for Send CB to
  // get the status of Trasnmitted packet
  esp_now_set_self_role(ESP_NOW_ROLE_CONTROLLER);

  // Once ESPNow is successfully Init, we will register for Send CB to
  // get the status of Trasnmitted packet
  esp_now_set_self_role(ESP_NOW_ROLE_CONTROLLER);
  esp_now_register_send_cb(OnDataSent);

  //Préparer les données à transmettre
  myData.topic = BOARD_ID;
  strcpy(myData.payload, "&1");
 
  Serial.println("\nMyData : " );
  Serial.println(*((uint8_t *) &myData.topic));
  Serial.println(*((uint8_t *) &myData.payload));
  Serial.println("\n");
  //Send data
  esp_now_send(broadcastAddress, (uint8_t *) &myData, sizeof(myData));

}


void loop() {
 
}

Receiver code

Code: Select all#include <espnow.h>
#include <ESP8266WiFi.h>

// Structure example to receive data
// Must match the sender structure
typedef struct struct_message {
  int topic;
  char payload[2];
} struct_message;

struct_message incomingReadings;

// callback function that will be executed when data is received
void OnDataRecv(uint8_t * mac_addr, uint8_t *incomingData, uint8_t len) {
  // send the received data to the Raspberry Pi
  // copier les résultats en mémoire
  memcpy(&incomingReadings, incomingData, sizeof(incomingReadings));
  //cout<<incomingReadings.topic<<incomingReadings.payload;
  Serial.printf("%d%s\n",incomingReadings.topic,incomingReadings.payload);
 
}


void setup() {
  // Initialize Serial Monitor
  Serial.begin(9600);

  // Set the device as a Station and Soft Access Point simultaneously
  WiFi.mode(WIFI_AP_STA);

  // Init ESP-NOW
  if (esp_now_init() != 0) {
    Serial.println("Error initializing ESP-NOW");
    return;}
  else{
    Serial.println("Initializing ESP-NOW completed");
  }

  // Once ESPNow is successfully Init, we will register for recv CB to
  // get recv packer info
  esp_now_register_recv_cb(OnDataRecv);

}

  void loop() {

}

I have already done some basic checks: MAC address, reboot of the 2 boards, distance between the boards, prints in the code, ... But I can find absolutely nothing, everything seems to be correct.

- Sat Apr 24, 2021 4:42 pm #91205 I found the problem. This is a buffer overflow.
I had to declare : char payload [3].
I also flash my board completely in Arduino IDE.