Safety timer (disable heaters after 15min idle)

Firmware/Timer.cpp

@@ -0,0 +1,55 @@
+/**
+ * @file
+ * @author Marek Bel
+ */
+
+#include "Timer.h"
+#include "Arduino.h"
+
+Timer::Timer() : m_isRunning(false), m_started()
+{
+}
+
+/**
+ * @brief Start timer
+ */
+void Timer::start()
+{
+    m_started = millis();
+    m_isRunning = true;
+}
+
+/**
+ * @brief Timer has expired
+ *
+ * Timer is considered expired after msPeriod has passed from time the timer was started.
+ * This function must be called at least each (unsigned long maximum value - msPeriod) milliseconds to be sure to
+ * catch first expiration.
+ * This function is expected to handle wrap around of time register well.
+ *
+ * @param msPeriod Time interval in milliseconds.
+ * @retval true Timer has expired
+ * @retval false Timer not expired yet, or is not running, or time window in which is timer considered expired passed.
+ */
+bool Timer::expired(unsigned long msPeriod)
+{
+    if (!m_isRunning) return false;
+    bool expired = false;
+    const unsigned long now = millis();
+    if (m_started <=  m_started + msPeriod)
+    {
+        if ((now >= m_started + msPeriod) || (now < m_started))
+        {
+            expired = true;
+        }
+    }
+    else
+    {
+        if ((now >= m_started + msPeriod) && (now < m_started))
+        {
+            expired = true;
+        }
+    }
+    if (expired) m_isRunning = false;
+    return expired;
+}