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<h3>Week 7: Outputs</h3>
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<a id="btn" href="wk7.zip" download>Download my files from this week!
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<h4>Assignment: Minimum Viable Product for Final Project</h4>
My MVP was developed across 2 states, using 3 weeks of research, dozens of Arudiono IDE crashes, and 1 fried ESP32.
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The process? Deeply frustrating. The product? Pretty good.
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<img src="light.gif" width = 400 alt="an Arduino and breadboard wired up with multiple buttons, resistors, and an LED">
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<p class="caption">Completed VO of "Spend the Night Light"
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<h4>Sender Code</h4>
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<pre><code>
#include <esp_now.h>
#include <WiFi.h>
uint8_t broadcastAddress[] = {0x08, 0xD1, 0xF9, 0x38, 0x16, 0x74};
// Structure example to send data
// Must match the receiver structure
typedef struct struct_message {
int delay;
} struct_message;
// Create a struct_message called myData
struct_message myData;
esp_now_peer_info_t peerInfo;
const int buttonPin = 27; // Assuming the button is connected to GPIO 2
bool buttonPressed = false;
// 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");
}
void setup() {
// Init Serial Monitor
Serial.begin(115200);
// 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 Transmitted 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;
}
// Set up the button pin
pinMode(buttonPin, INPUT_PULLUP);
}
void loop() {
// Check if the button is pressed
if (digitalRead(buttonPin) == LOW && !buttonPressed) {
// Set values to send
myData.delay = 2;
// Send message via ESP-NOW
esp_err_t result = esp_now_send(broadcastAddress, (uint8_t *) &myData, sizeof(myData));
if (result == ESP_OK) {
Serial.println("Sent with success");
}
else {
Serial.println("Error sending the data");
}
// Set buttonPressed to true to prevent further messages until the button is released and pressed again
buttonPressed = true;
}
// Check if the button is released
else if (digitalRead(buttonPin) == HIGH && buttonPressed) {
// Reset buttonPressed to false so that a message can be sent again when the button is pressed
buttonPressed = false;
}
// Delay before checking the button state again
}
</code></pre>
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<h4>Receiver Code</h4>
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<pre><code>
#include <esp_now.h>
#include <WiFi.h>
// Structure example to receive data
// Must match the sender structure
typedef struct struct_message {
int delay;
} struct_message;
// Create a struct_message called myData
struct_message myData;
const int ledPin = 27;
unsigned long timeToTurnOff = 0;
// callback function that will be executed when data is received
void OnDataRecv(const uint8_t * mac, const uint8_t *incomingData, int len) {
memcpy(&myData, incomingData, sizeof(myData));
digitalWrite(ledPin, HIGH);
timeToTurnOff = millis() + myData.delay * 1000;
}
void setup() {
pinMode(ledPin, OUTPUT);
// Initialize Serial Monitor
Serial.begin(115200);
// 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 recv CB to
// get recv packer info
esp_now_register_recv_cb(OnDataRecv);
}
void loop() {
if (millis() >= timeToTurnOff){
digitalWrite(ledPin, LOW);
}
}
</code></pre>
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<h4>RandomNerdTutorials Basic Code: Send Message on Startup</h4>
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<pre><code>
#include <WiFi.h>
#include <HTTPClient.h>
const char* ssid = "your_wifi_ssid";
const char* password = "your_wifi_password";
const char* apiKey = "your_callmebot_api_key";
void setup() {
Serial.begin(115200);
delay(100);
// Connect to Wi-Fi
Serial.println();
Serial.println("Connecting to WiFi");
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
Serial.println("WiFi connected");
}
void loop() {
if (WiFi.status() == WL_CONNECTED) {
HTTPClient http;
// Your message to be sent
String message = "Hello from ESP32!";
// Construct the API URL
String url = "https://api.callmebot.com/whatsapp.php?phone=YOUR_PHONE_NUMBER&text=" + message + "&apikey=" + apiKey;
Serial.print("Sending request to: ");
Serial.println(url);
// Send HTTP POST request
http.begin(url);
int httpResponseCode = http.GET();
if (httpResponseCode > 0) {
Serial.print("HTTP Response code: ");
Serial.println(httpResponseCode);
String payload = http.getString();
Serial.println(payload); // Print response payload
} else {
Serial.print("Error code: ");
Serial.println(httpResponseCode);
}
http.end();
}
delay(60000); // Send the message every 1 minute
}
</code></pre>
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V0 used two external power sources from USB chargers. These or AA batteries will likely power the final version.
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<img src="range test.jpeg" width = 700 alt="an Arduino and breadboard wired up with multiple buttons, resistors, and an LED">
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<p class="caption">Science Center range test: hallway outside the lab.</p>
The ESP Now was functional at 50 meters. Although I couldn't see the light from any further, it seemed to work beyond this distance. This is more than enough for the application.
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<h4>MVP Stage Two: New Features</h4>
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