Dealing with ESP_NOW

Projects Programming
1

In this code I need to call the function after the code of adding peer, but I have problem in the output of the function, why the output of the function is correct when call it before WiFi.mode and the output is incorrect number when call it after the Add peer ? what happen!!

#include <esp_now.h>
#include <WiFi.h>
// REPLACE WITH YOUR RECEIVER MAC Address
uint8_t broadcastAddress[] = { 0x24, 0x22, 0xAB, 0xE0, 0x34, 0x51};
//#define LENGTH 500
//unsigned char data[LENGTH] = {0};
esp_now_peer_info_t peerInfo;

int8_t data[]={88,86,86,85,85,83,83,83,83,83,83,84,84,85,85,85,85,85,85,85};
// 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");
}

struct result {
    size_t outSize;
    unsigned char *bytes;
};
result strc;

void Send_ESP_Data(int8_t data[]) {
   for( int i=0;i<20;i++){
      strc.outSize +=data[i];
   }
}

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

 Send_ESP_Data(data);
 Serial.printf("outSize befor Add peer =%i \n ",strc.outSize);
 // Set device as a Wi-Fi Station
  WiFi.mode(WIFI_STA);

  // Init ESP-NOW
  if (esp_now_init() != ESP_OK) {
    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_register_send_cb(OnDataSent);
  // 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;
  }              
 Send_ESP_Data(data);    // the calling here gave me incorrect result
Serial.printf("outSize after Add peer =%i \n ",strc.outSize);
int sendoutSize = strc.outSize;

// Here I want to use esp_now_send(broadcastAddress);
  
}//end setup

void loop() {} // repeat the lines of code below
2

you define

struct result {
    size_t outSize;
    unsigned char *bytes;
};
result strc;

as strc is a global variable strc.outSize will be initialiased to 0
when you call

void Send_ESP_Data(int8_t data[]) {
   for( int i=0;i<20;i++){
      strc.outSize +=data[i];
   }
}

the first time it will start adding the data[i] to 0 ending with 1691
the second call will starting adding data[i] to 1691 ending with 3382

I note that the structure results contains a pointer

    unsigned char *bytes;

are you intending to point this at the data to transmit?
if so it will not work - it will transmit the pointer value (which points to the address in memory where the data is stored) which will mean nothing to the receiver