How do I connect relay module to wifi control by esp32

[ahmedfotoh]

I'm using esp_now(transmitter & receiver) to switch relays on/off ( relays on at LOW signal) the problem is when power on receiver circuit ,esp32 and relay module at the same time,(relay module connected to +ve & -ve pins of esp32), there's no signal at receiver and showing error (invalid header) in serial monitor , but when power on esp32 first then connect relay module terminal to +ve & -ve pins ,it is working right .I need to solve this problem(power on all circuit at the same time. . the code of receiver

Code: Select all

#include <esp_now.h>
#include <WiFi.h>
#define LED_Pin1   4
#define LED_Pin2   12
typedef struct struct_message {
    int led1;
    int led2;
} struct_message ;
struct_message receive_Data; // Create a struct_message to receive data.
void OnDataRecv(const uint8_t * mac, const uint8_t *incomingData, int len) {
  memcpy(&receive_Data, incomingData, sizeof(receive_Data));
  Serial.println();
  Serial.println("<<<<< Receive Data:");
  Serial.print("Bytes received: ");
  Serial.println(len);
 digitalWrite(LED_Pin1, receive_Data.led1);
  digitalWrite(LED_Pin2, receive_Data.led2);
  Serial.println("<<<<<"); 
}
void setup(){
  Serial.begin(115200);
       digitalWrite(LED_Pin1, HIGH);
   digitalWrite(LED_Pin2, HIGH);
  pinMode(LED_Pin1, OUTPUT);
  pinMode(LED_Pin2, OUTPUT);
  WiFi.mode(WIFI_STA);
  if (esp_now_init() != ESP_OK) {
    Serial.println("Error initializing ESP-NOW");
    return;
  }
  esp_now_register_recv_cb(OnDataRecv); 
}
void loop(){}

[lbernstone]

The gpio pins on an esp32 are only rated for 42mA, so you probably are having some power dips. Use a gpio on a mosfet (or any transistor) to gate power directly from the power supply.