RTC Alarm

This page provides two key examples for using the real-time clock (RTC) on the Inkplate 2. The examples demonstrate how to retrieve the current time from the internet and how to set a periodic wake-up alarm using Inkplate's RTC functionality.

---

Example 1: fetching time from the internet

This example shows how to use the Network object to retrieve the current date and time from an NTP server and display it on the screen.

#include "Inkplate.h"
#include "Network.h"

Inkplate display;
Network network;

char ssid[] = "your-ssid";
char pass[] = "your-password";
int timeZone = 2;

struct tm currentTime;
#define DELAY_TIME 40 * 1000

void setup() {
    Serial.begin(115200);
    network.begin(ssid, pass);
    display.begin();
    display.setTextColor(INKPLATE2_BLACK);
}

void loop() {
    network.getTime(&currentTime, timeZone);

    display.clearDisplay();
    display.setCursor(0, 10);
    display.setTextSize(7);
    display.printf("%2.1d:%02d\n", currentTime.tm_hour, currentTime.tm_min);
    display.setTextSize(3);
    display.printf(" %2.1d.%2.1d.%04d\n", currentTime.tm_mday, currentTime.tm_mon + 1, currentTime.tm_year + 1900);
    display.display();

    delay(DELAY_TIME);
}

This will print the current time and date based on your time zone, updated approximately every 40 seconds.

---

Example 2: periodic alarm wake-up

This example sets an RTC alarm that triggers periodically (every 1 hour and 30 minutes) and checks whether the target date/time has been reached.

#include "Inkplate.h"
#include "Network.h"
#include "RTC.h"

Inkplate display;
Network network;
RTC rtc;

char ssid[] = "your-ssid";
char pass[] = "your-password";
int timeZone = 1;

int alarmHour = 8, alarmMins = 0, alarmSecs = 0, alarmDay = 25, alarmMon = 12;
int wakeHours = 1, wakeMinutes = 30;

struct tm currentTime;

void setup() {
    Serial.begin(115200);
    network.begin(ssid, pass);
    network.getTime(&currentTime, timeZone);

    display.begin();
    display.clearDisplay();
    display.setTextColor(INKPLATE2_BLACK);

    int timeUntilAlarmInSeconds = rtc.secondsUntilAlarm(alarmHour, alarmMins, alarmSecs, alarmDay, alarmMon, currentTime);

    if (timeUntilAlarmInSeconds <= 0) {
        alarmScreen();
        while (1) delay(100);
    } else {
        waitingScreen();
        rtc.setWakeUpTimer(wakeHours, wakeMinutes, currentTime);
        esp_deep_sleep_start();
    }
}

void loop() {}

void waitingScreen() {
    display.setTextSize(1);
    display.printf("\n           Waiting for: ");
    display.setTextSize(4);
    display.setCursor(0, 33);
    display.printf("  %2.1d:%02d", alarmHour, alarmMins);
    display.setCursor(0, 65);
    display.setTextSize(2);
    display.printf("    on %2.1d.%2.1d.", alarmDay, alarmMon);
    display.display();
}

void alarmScreen() {
    display.setTextSize(2);
    display.setCursor(9, 30);
    display.printf("ALARM!\n");
    display.setTextSize(1);
    display.display();
}

This will keep the Inkplate in deep sleep, waking every 1.5 hours to check if the set alarm time has arrived.

---

Full examples

Inkplate2_RTC_Alarm.ino

Displays time and date fetched from an NTP server

Inkplate2_RTC_Alarm_Periodic.ino

Periodically checks for a predefined alarm time and triggers a screen update