Skip to content

14. Networking and communications

Group assignment

This week we played around with input devices, and measured the data that they send.

Commandeering WiFi

Software used this week

  • Arduino IDE
  • KiCad

Finished things

I had trouble thinking up castable object that would be needed in a pinball machine. Almost all parts would be more sturdy when cast, but the designs are not ready for that yet.

So I decided to create the following objects:

  • Internal dialogue alt text I made a PCB for bumper, and had it communicate with the main board with I2C. I2C

Code for the group work

Code used in group work 
/*********
  Rui Santos
  Complete project details at https://RandomNerdTutorials.com/esp-now-one-to-many-esp32-esp8266/

  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files.

  The above copyright notice and this permission notice shall be included in all
  copies or substantial portions of the Software.
*********/

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

// REPLACE WITH YOUR ESP RECEIVER'S MAC ADDRESS
uint8_t broadcastAddress1[] = {0x34, 0x85, 0x18, 0x05, 0x0C, 0x7C};
uint8_t broadcastAddress2[] = {0x34, 0x85, 0x18, 0x03, 0x69, 0x24};

typedef struct test_struct {
  int x;
  int y;
} test_struct;

test_struct test;

esp_now_peer_info_t peerInfo;

// callback when data is sent
void OnDataSent(const uint8_t *mac_addr, esp_now_send_status_t status) {
  char macStr[18];
  Serial.print("Packet to: ");
  // Copies the sender mac address to a string
  snprintf(macStr, sizeof(macStr), "%02x:%02x:%02x:%02x:%02x:%02x",
          mac_addr[0], mac_addr[1], mac_addr[2], mac_addr[3], mac_addr[4], mac_addr[5]);
  Serial.print(macStr);
  Serial.print(" send status:\t");
  Serial.println(status == ESP_NOW_SEND_SUCCESS ? "Delivery Success" : "Delivery Fail");
}

void setup() {
  Serial.begin(115200);

  WiFi.mode(WIFI_STA);

  if (esp_now_init() != ESP_OK) {
    Serial.println("Error initializing ESP-NOW");
    return;
  }

  esp_now_register_send_cb(OnDataSent);

  // register peer
  peerInfo.channel = 0;  
  peerInfo.encrypt = false;
  // register first peer  
  memcpy(peerInfo.peer_addr, broadcastAddress1, 6);
  if (esp_now_add_peer(&peerInfo) != ESP_OK){
    Serial.println("Failed to add peer");
    return;
  }
  // register second peer  
  memcpy(peerInfo.peer_addr, broadcastAddress2, 6);
  if (esp_now_add_peer(&peerInfo) != ESP_OK){
    Serial.println("Failed to add peer");
    return;
  }
}



void loop() {

  if (Serial.available()) {
    char byte = Serial.read();

    int y = atoi(&byte);

    test.y = y;

  }

  test.x = test.x +1;

  if (test.x > 50) { test.x = 0; test.y = test.y +1; }
  if (test.y > 50) test.y = 0;

  esp_err_t result = esp_now_send(0, (uint8_t *) &test, sizeof(test_struct));

  if (result == ESP_OK) {
    char strBuf[50];
    sprintf(strBuf, "Sent with success %d, %d", test.x, test.y);
    Serial.println(strBuf);
  }
  else {
    Serial.println("Error sending the data");
  }

  delay(2000);
}

Original code was copied from: https://randomnerdtutorials.com/esp-now-one-to-many-esp32-esp8266/#more-95718

Changes include:

  • Reducing the number of connections from three to two
  • Writing the correct MAC addresses for the connections
  • Reads data from Serial, and sends it through ESP NOW