Merge pull request #56 from blackleg/interrupts

Add interruption example

Author: feilipu

examples/Interrupts/Interrupts.ino

@@ -0,0 +1,78 @@
+/*
+ * Example of a Arduino interruption and RTOS Binary Semaphore
+ * https://www.freertos.org/Embedded-RTOS-Binary-Semaphores.html
+ */
+
+
+// Include Arduino FreeRTOS library
+#include <Arduino_FreeRTOS.h>
+
+// Include semaphore supoport
+#include <semphr.h>
+
+/* 
+ * Declaring a global variable of type SemaphoreHandle_t 
+ * 
+ */
+SemaphoreHandle_t interruptSemaphore;
+
+void setup() {
+
+  // Configure pin 2 as an input and enable the internal pull-up resistor
+  pinMode(2, INPUT_PULLUP);
+
+ // Create task for Arduino led 
+  xTaskCreate(TaskLed, // Task function
+              "Led", // Task name
+              128, // Stack size 
+              NULL, 
+              0, // Priority
+              NULL );
+
+  /**
+   * Create a binary semaphore.
+   * https://www.freertos.org/xSemaphoreCreateBinary.html
+   */
+  interruptSemaphore = xSemaphoreCreateBinary();
+  if (interruptSemaphore != NULL) {
+    // Attach interrupt for Arduino digital pin
+    attachInterrupt(digitalPinToInterrupt(2), interruptHandler, LOW);
+  }
+
+  
+}
+
+void loop() {}
+
+
+void interruptHandler() {
+  /**
+   * Give semaphore in the interrup handler
+   * https://www.freertos.org/a00124.html
+   */
+  
+  xSemaphoreGiveFromISR(interruptSemaphore, NULL);
+}
+
+
+/* 
+ * Led task. 
+ */
+void TaskLed(void *pvParameters)
+{
+  (void) pvParameters;
+
+  pinMode(LED_BUILTIN, OUTPUT);
+
+  for (;;) {
+    
+    /**
+     * Take the semaphore.
+     * https://www.freertos.org/a00122.html
+     */
+    if (xSemaphoreTake(interruptSemaphore, portMAX_DELAY) == pdPASS) {
+      digitalWrite(LED_BUILTIN, !digitalRead(LED_BUILTIN));
+    }
+    
+  }
+}