ESP32 Forum

Posted: **Fri Jul 07, 2023 11:02 pm**

hey. I am new to ESP-32 programming, so little bit stuck with a small (I hope) issue.
I am trying to make a simple peer-to-peer communication between two ESP-32 controllers. the first one is getting data from BME-280 and sending it to the second one.
very easy. a lot of examples in the internet, but I have a problem. the first board is sending the data only once. after that the callback function esp_now_register_send_cb(OnDataSent) is not called and data is not actually sending.
the code:

Code: Select all

#include <esp_now.h>
#include <WiFi.h>

#include <Wire.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BME280.h>

#define I2C_SDA 33 
#define I2C_SCL 32 
TwoWire I2CSensors = TwoWire(0);

const char* ssid = "xxxxxxx";
const char* password = "xxxxxxxxx";


uint8_t broadcastAddress[] = {0x78, 0xE3, 0x6D, 0x16, 0xF6, 0x84};

Adafruit_BME280 bme;

// Define variables to store BME280 readings to be sent
float temperature;
float humidity;
float pressure;

//Structure example to send data
//Must match the receiver structure
typedef struct struct_message {
    float temp;
    float hum;
    float pres;
} struct_message;

// Create a struct_message called BME280Readings to hold sensor readings
struct_message BME280Readings;

esp_now_peer_info_t peerInfo;

// Callback when data is sent
void OnDataSent(const uint8_t *mac_addr, esp_now_send_status_t status) {
  Serial.print("\r\nLast Packet Send Status:\t");
  Serial.println(status == ESP_NOW_SEND_SUCCESS ? "Delivery Success" : "Delivery Fail");
}

// Callback when data is received
void OnDataRecv(const uint8_t * mac, const uint8_t *incomingData, int len) {
  Serial.print("Request bytes received: ");
  Serial.println(len);
}

void setup(){
  // Init Serial Monitor
  Serial.begin(115200);

  // Connect to Wi-Fi
  WiFi.mode(WIFI_STA);
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);
  WiFi.begin(ssid, password);
  uint32_t notConnectedCounter = 0;
  Serial.print("Wifi connecting");
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
    notConnectedCounter++;
    if(notConnectedCounter > 50) { 
        Serial.println("Resetting due to Wifi not connecting...");
        ESP.restart();
    }
  }
  Serial.println();
  Serial.print("ESP32-CAM IP Address: ");
  Serial.println(WiFi.localIP()); 

  I2CSensors.begin(I2C_SDA, I2C_SCL, 100000);
  if (!bme.begin(0x76, &I2CSensors))
  {
    Serial.println("Couldn't Find BME280 Sensor");
    while(1);
  }
  else
  {
    Serial.println("BME280 Sensor Found");
  }
  
  // Init ESP-NOW
  if (esp_now_init() != ESP_OK) {
    Serial.println("Error initializing ESP-NOW");
    return;
  }

  // Register peer
  memcpy(peerInfo.peer_addr, broadcastAddress, 6);
  peerInfo.channel = 0;  
  peerInfo.encrypt = false;
  
  // Add peer        
  if (esp_now_add_peer(&peerInfo) != ESP_OK) {
    Serial.println("Failed to add peer");
    return;
  }
  if (esp_now_register_recv_cb(OnDataRecv) != ESP_OK) {
    Serial.println("Failed to add OnDataRecv callback");
    return;
  }
  if (esp_now_register_send_cb(OnDataSent) != ESP_OK) {
    Serial.println("Failed to add OnDataSent callback");
    return;
  };
}

void loop() {
    getReadings();
 
    // Set values to send
    BME280Readings.temp = temperature;
    BME280Readings.hum = humidity;
    BME280Readings.pres = pressure;

    // Send message via ESP-NOW
    esp_err_t result = esp_now_send(broadcastAddress, (uint8_t *) &BME280Readings, sizeof(BME280Readings));
    if (result == ESP_OK) {
      Serial.println("Sent with success");
    }
    else {
      Serial.println("Error sending the data");
    } 
    delay(3000);
}

void getReadings(){
  temperature = bme.readTemperature();
  humidity = bme.readHumidity();
  pressure = (bme.readPressure() / 100.0F);
}

what I have in serial:

Code: Select all

Wifi connecting....
ESP32-CAM IP Address: 192.168.0.89
BME280 Sensor Found
Sent with success

Last Packet Send Status:	Delivery Fail
Sent with success
Sent with success
Sent with success
Sent with success
Sent with success
Error sending the data
Error sending the data
Error sending the data
Error sending the data
Error sending the data
Error sending the data
Error sending the data

actually it sends only once. and after that just messages "sent with success" without sending the data (receiver doesn't get it) and "error sending data"...

anybody knows what could be the problem?
thanks!

Posted: **Sat Jul 08, 2023 11:18 am**

Check the return value of the esp_now_send function. If the return value is not ESP_OK, you can use the esp_err_to_name function to convert the error code to a human-readable string and print it for debugging purposes. For example:

Code: Select all

esp_err_t result = esp_now_send(broadcastAddress, (uint8_t *) &BME280Readings, sizeof(BME280Readings));
if (result == ESP_OK) {
  Serial.println("Sent with success");
} else {
  Serial.print("Error sending the data: ");
  Serial.println(esp_err_to_name(result));
}

This will provide more specific information about the error that might help you identify the issue.

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