Example/interrupt

examples/AlarmInterrupt/AlarmInterrupt.ino

@@ -0,0 +1,68 @@
+/*
+AlarmInterrupt.ino
+Jacob Nuernberg
+08/22
+
+Example on using interrupts with DS3231 alarms.
+
+Connect DS3231 SQW pin to Arduino interrupt pin 2
+
+Tested on:
+- Arduino UNO
+- Arduino nano
+
+*/
+
+#include <DS3231.h>
+#include <Wire.h>
+
+// myRTC interrupt pin
+#define CLINT 2
+
+// Setup clock
+DS3231 myRTC;
+
+// Interrupt signaling byte
+volatile byte tick = 1;
+
+void setup() {
+    // Begin I2C communication
+    Wire.begin();
+
+    // Setup alarm one to fire every second
+    myRTC.turnOffAlarm(1);
+    myRTC.setA1Time(0, 0, 0, 0, 0b01111111, false, false, false);
+    myRTC.turnOnAlarm(1);
+    myRTC.checkIfAlarm(1);
+
+    // attach clock interrupt
+    pinMode(CLINT, INPUT_PULLUP);
+    attachInterrupt(digitalPinToInterrupt(CLINT), isr_TickTock, FALLING);
+
+    // Use builtin LED to blink
+    pinMode(LED_BUILTIN, OUTPUT);
+}
+
+void loop() {
+    // static variable to keep track of LED on/off state
+    static byte state = false;
+
+    // if alarm went of, do alarm stuff
+    if (tick) {
+        tick = 0;
+        state = ~state;
+        digitalWrite(LED_BUILTIN, state);
+        // Clear alarm state
+        myRTC.checkIfAlarm(1);
+    }
+
+    // Loop delay to emulate other running code
+    delay(10);
+}
+
+
+void isr_TickTock() {
+    // interrupt signals to loop
+    tick = 1;
+    return;
+}