Modifications to demonstrate FreeRTOS task creation and mutex operations running on an AdaFruit ItsyBitsy nRF52840 Express board.

Author: Michael Polia

examples/Mutex/Mutex.ino

@@ -3,8 +3,8 @@
    https://www.freertos.org/Real-time-embedded-RTOS-mutexes.html
 */
 
-// Include Arduino FreeRTOS library
-#include <Arduino_FreeRTOS.h>
+#include <Arduino.h>
+#include <Adafruit_TinyUSB.h> // for Serial
 
 
 // Include mutex support
@@ -20,62 +20,81 @@ int globalCount = 0;
 
 void setup() {
 
-  Serial.begin(9600);
-
-  /**
-       Create a mutex.
-       https://www.freertos.org/CreateMutex.html
-  */
-  mutex = xSemaphoreCreateMutex();
-  if (mutex != NULL) {
-    Serial.println("Mutex created");
-  }
-
-  /**
-     Create tasks
-  */
-  xTaskCreate(TaskMutex, // Task function
-              "Task1", // Task name for humans
-              128, 
-              1000, // Task parameter
-              1, // Task priority
-              NULL);
-
-  xTaskCreate(TaskMutex, "Task2", 128, 1000, 1, NULL);
+    Serial.begin(115200);
 
-}
+    // Wait for a serial port connection to be established before continuing.
+    // Don't want to miss any debug messages.
+    while ( !Serial ) delay(10);   // for nrf52840 with native usb
 
-void loop() {}
+    Serial.println("STARTING THE APPLICATION.");
 
-void TaskMutex(void *pvParameters)
-{
-  TickType_t delayTime = *((TickType_t*)pvParameters); // Use task parameters to define delay
+    /**
+        Create a mutex.
+        https://www.freertos.org/CreateMutex.html
+    */
+    mutex = xSemaphoreCreateMutex();
+    if (mutex != NULL) {
+        Serial.println("Mutex created");
+    }
+    else {
+        Serial.println("ERROR! Mutex creation failed!");
+    }
 
-  for (;;)
-  {
     /**
-       Take mutex
-       https://www.freertos.org/a00122.html
+        Create tasks.
+        Relative task periodicity is offset by 200 mSec.
     */
-    if (xSemaphoreTake(mutex, 10) == pdTRUE)
-    {
-      Serial.print(pcTaskGetName(NULL)); // Get task name
-      Serial.print(", Count read value: ");
-      Serial.print(globalCount);
+    xTaskCreate(TaskMutex, // Task function
+    "Task1", // Task name for humans
+    128, 
+    (void*)900, // Task parameter
+    1, // Task priority
+    NULL);
+
+    xTaskCreate(TaskMutex, "Task2", 128, (void*)1100, 1, NULL);
+}
 
-      globalCount++;
+void loop() {
+    Serial.println("...looping...");
+    delay(1000);
+}
 
-      Serial.print(", Updated value: ");
-      Serial.print(globalCount);
+void TaskMutex(void *pvParameters)
+{
+    TickType_t delayTime = ((TickType_t)pvParameters); // Use task parameters to define delay
 
-      Serial.println();
-      /**
-         Give mutex
-         https://www.freertos.org/a00123.html
-      */
-      xSemaphoreGive(mutex);
-    }
+    Serial.print("Starting task ");
+    Serial.print(pcTaskGetName(NULL)); // Get task name
+    Serial.print(" with delay ");
+    Serial.println(delayTime);
+    delay(1000);
 
-    vTaskDelay(delayTime / portTICK_PERIOD_MS);
-  }
+    for (;;)
+    {
+        /**
+        Take mutex
+        https://www.freertos.org/a00122.html
+        */
+        if (xSemaphoreTake(mutex, 10) == pdTRUE)
+        {
+            Serial.print(pcTaskGetName(NULL)); // Get task name
+            Serial.print(", Count read value: ");
+            Serial.print(globalCount);
+
+            globalCount++;
+
+            Serial.print(", Updated value: ");
+            Serial.print(globalCount);
+
+            Serial.println();
+            /**
+            Give mutex
+            https://www.freertos.org/a00123.html
+            */
+            xSemaphoreGive(mutex);
+        }
+
+        // Add '1' to prevent divide by zero compilation error.
+        vTaskDelay(delayTime / (1 + portTICK_PERIOD_MS));
+    }
 }