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listen.ino
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listen.ino
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#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <WiFi.h>
#include <WiFiClientSecure.h>
#include <HTTPClient.h>
#include <ArduinoJson.h>
#include <TimeLib.h>
// setup lcd display
LiquidCrystal_I2C lcd(0x27, 16, 2);
// init the http and wifi objects
HTTPClient http;
WiFiClientSecure wifi;
const char* ssid = "AAAA";
const char* password = "BBBB";
const char* url = "https://sce.sjsu.edu/api/messages/listen?id=XXXX&apiKey=YYYY";
void setup() {
Serial.begin(115200);
lcd.init();
lcd.backlight();
lcd.setCursor(0, 0);
// connect to wifi network
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(1000);
lcd.setCursor(0, 0);
lcd.print("Connecting");
lcd.setCursor(0, 1);
lcd.print("to the WiFi...");
}
lcd.clear();
lcd.print("Connected.");
delay(1000);
wifi.setInsecure();
// Connect to the SSE endpoint
http.setReuse(true);
http.begin(wifi, url);
http.addHeader("Connection", "keep-alive");
// This part of the code waits for the first message to be typed in the room.
int responseCode;
while (responseCode < 0) {
lcd.clear();
lcd.print("Waiting for a");
lcd.setCursor(0, 1);
lcd.print("message....");
responseCode = http.GET();
delay(500);
}
}
void loop() {
if (http.connected()) {
if (wifi.available()) {
String line = wifi.readStringUntil('\n');
if (line.startsWith("data: ")) {
String jsonString = line.substring(6).c_str();
JsonDocument doc;
deserializeJson(doc, jsonString);
const long long unsigned int currentTime = doc["timestamp"];
const char* currentMessage = doc["message"];
time_t currentTimeConverted = time_t(currentTime / 1000);
// Logic to display the message
lcd.clear();
flushWiFiBuffer(); // flush the buffer so scrollMessage properly runs
lcd.setCursor(0, 0);
String timeFormatted = getDateTime(currentTimeConverted);
lcd.print(timeFormatted);
scrollMessage(1, currentMessage, 250, 16);
lcd.setCursor(0, 1);
lcd.print(currentMessage);
}
}
} else {
// Attempt to reconnect if the server crashes
int responseCode = -1;
while (responseCode < 0) {
lcd.clear();
lcd.print("Reconnecting");
lcd.setCursor(0, 1);
lcd.print("and waiting...");
responseCode = http.GET();
delay(500);
}
}
delay(500);
}
// Function to scroll the message
void scrollMessage(int row, String message, int delayTime, int lcdColumns) {
for (int i = 0; i < lcdColumns; i++) {
message = " " + message;
}
message = message + " ";
for (int pos = 0; pos < message.length(); pos++) {
lcd.setCursor(0, row);
lcd.print(message.substring(pos, pos + lcdColumns));
delay(delayTime);
}
}
// flush whatever is in the buffer so that the next messages that are supposed to display actually displays properly
void flushWiFiBuffer() {
while (wifi.available()) {
wifi.read();
}
}
// formats epoch time to a readable format
String getDateTime(time_t t) {
String formattedDate = String(month(t)) + "/" + String(day(t)) + "/" + String(year(t));
String hourString = String(hour(t));
if (hour(t) < 10) {
hourString = "0" + hourString;
}
String minuteString = String(minute(t));
if (minute(t) < 10) {
minuteString = "0" + minuteString;
}
return formattedDate + " " + hourString + ":" + minuteString;
}