ESP8266 - ESP-Now Delivery Failure, but only sometimes

[chrismast]

He, sorry for my late reply and thanks for your comment.
Did not have much time over the last days to work on the ESP8266 project, whereas I found out that it indeed is somehow connected to the WiFi channel (i.e. my AP was using channel 6, whereas ESP-Now supposedly only (?) works on 1).

I wrote some test code and used the following WiFi and ESP-Now config which in a first test seemed to work, at least all deliveries were a success.

My test code for reference below.

Coordinator:

#include <Arduino.h>
#include <ESP8266WiFi.h>
#include <espnow.h>
//#include <PubSubClient.h>

#include "network.h"

// WIFI and MQTT
//WiFiClient espClient;
//PubSubClient client(espClient);

// Structure example to receive data
// Must match the sender structure
typedef struct struct_message {
    char a[32];
    int b;
    float c;
    String d;
    bool e;
} struct_message;

// Create a struct_message called myData
struct_message myData;

// Callback function that will be executed when data is received
void OnDataRecv(uint8_t * mac, uint8_t *incomingData, uint8_t len) {
  memcpy(&myData, incomingData, sizeof(myData));
  Serial.print("Bytes received: ");
  Serial.println(len);
  Serial.print("Char: ");
  Serial.println(myData.a);
  //client.publish("masterbathroom/shower/a", myData.a);
  Serial.print("Int: ");
  Serial.println(myData.b);
  
  char myDatab[32];
  String myDatab_str;
  myDatab_str = String(myData.b);
  myDatab_str.toCharArray(myDatab, myDatab_str.length() + 1);
  
  //client.publish("masterbathroom/shower/b", myDatab);
  Serial.print("Float: ");
  Serial.println(myData.c);
  Serial.print("String: ");
  Serial.println(myData.d);
  Serial.print("Bool: ");
  Serial.println(myData.e);
  Serial.println();
}
 
void setup() {
  // Initialize Serial Monitor
  Serial.begin(115200);
  
  // Set device as a Wi-Fi Station
  WiFi.mode(WIFI_AP_STA);

  // Set device as a Wi-Fi Station
  WiFi.begin(ssid, password, channel, bssid);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Setting as a Wi-Fi Station..");
  }

  Serial.print("Station IP Address: ");
  Serial.println(WiFi.localIP());
  Serial.print("Wi-Fi Channel: ");
  Serial.println(WiFi.channel());
  
  //WiFi.config(staticIP, dns, gateway, subnet);
  //WiFi.begin(ssid, password, channel, bssid);
  //WiFi.persistent(true);
  //WiFi.setAutoConnect(true);
  //WiFi.setAutoReconnect(true);
  
  //while (WiFi.status() != WL_CONNECTED) {
  //delay(500);
  //}

  //Connect to MQTT - loop till connected
  //client.setServer(mqttServer, mqttPort);

  //while (!client.connected()) {
  // if (client.connect("WEMOS", mqttUser, mqttPassword)) {
  //  client.subscribe("masterbathroom/shower");
  //  } else {
  //   delay(500);
  //  }
  //}

  // Init ESP-NOW
  if (esp_now_init() != 0) {
    Serial.println("Error initializing ESP-NOW");
    return;
  }
  
  // Once ESPNow is successfully Init, we will register for recv CB to
  // get recv packer info
  esp_now_set_self_role(ESP_NOW_ROLE_SLAVE);
  esp_now_register_recv_cb(OnDataRecv);
}

void loop() {
  //client.loop();
}

Sender:

#include <Arduino.h>
#include <ESP8266WiFi.h>
#include <espnow.h>

// REPLACE WITH RECEIVER MAC Address
uint8_t broadcastAddress[] = {0x84, 0xCC, 0xA8, 0xA6, 0x1D, 0x7D};
uint8_t bssid[] = {0x18,0xE8,0x29,0xCC,0xF0,0x4E};

// Structure example to send data
// Must match the receiver structure
typedef struct struct_message {
  char a[32];
  int b;
  float c;
  String d;
  bool e;
} struct_message;

// Create a struct_message called myData
struct_message myData;

unsigned long lastTime = 0;  
unsigned long timerDelay = 2000;  // send readings timer
unsigned int readingId = 0;

// Insert your SSID
constexpr char WIFI_SSID[] = "IOT";

int32_t getWiFiChannel(const char *ssid) {
  if (int32_t n = WiFi.scanNetworks()) {
    for (uint8_t i=0; i<n; i++) {
      if (!strcmp(ssid, WiFi.SSID(i).c_str())) {
        return WiFi.channel(i);
      }
    }
  }
  return 0;
}

// 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");
  }
  else{
    Serial.println("Delivery fail");
  }
}
 
void setup() {
  // Init Serial Monitor
  Serial.begin(115200);
 
  // Set device as a Wi-Fi Station
  WiFi.mode(WIFI_STA);
  int32_t channel = getWiFiChannel(WIFI_SSID);

  WiFi.printDiag(Serial); // Uncomment to verify channel number before
  wifi_promiscuous_enable(1);
  wifi_set_channel(channel);
  wifi_promiscuous_enable(0);
  WiFi.printDiag(Serial); // Uncomment to verify channel change after

  // 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);
  esp_now_register_send_cb(OnDataSent);
  
  // Register peer
  esp_now_add_peer(broadcastAddress, ESP_NOW_ROLE_SLAVE, 1, NULL, 0);
}
 
void loop() {
  if ((millis() - lastTime) > timerDelay) {
    // Set values to send
    strcpy(myData.a, "THIS IS A CHAR");
    myData.b = random(1,20);
    myData.c = 1.2;
    myData.d = "Hello";
    myData.e = false;

    // Send message via ESP-NOW
    esp_now_send(broadcastAddress, (uint8_t *) &myData, sizeof(myData));

    lastTime = millis();
  }
}