sync

Documentation/ideas/FastFlash/README.md

@@ -0,0 +1,8 @@
+# FastFlash
+As we build ESP32 applications, we typically perform a compile, flash, test loop cycle.  We compile an app, we flash the ESP32 with that app and then we test whether it works.  We perform these actions over and over again.  When we look at the time taken in each step, we see there is compile time on our PC and then the time taken to flash the PC.  This story talks about the time taken to flash the PC.
+
+The ESP32 is typically configured to flash at 115200 kbps.  This is 115200 bits per second.  If we think that a typical ESP32 application is 800KBytes then this requires a transmission of:
+
+800000 * 9 = 7.2 million bits = 62.5 seconds
+
+we can increase our baud rate up to 921600 = 7.8 seconds

tasks/watchdogs/README.md

@@ -1,4 +1,4 @@
-#Watchdogs
+# Watchdogs
 This is a sample application that illustrates the capabilities of watchdogs and watchdog processing.
 
 A related YouTube video is available here:

tasks/watchdogs/main.cpp

@@ -0,0 +1,155 @@
+#include "freertos/FreeRTOS.h"
+#include "esp_wifi.h"
+#include "esp_system.h"
+#include "esp_event.h"
+#include "esp_event_loop.h"
+#include "nvs_flash.h"
+#include "driver/gpio.h"
+#include <esp_task_wdt.h>
+
+esp_err_t event_handler(void *ctx, system_event_t *event)
+{
+    return ESP_OK;
+}
+
+extern "C"
+{
+    void app_main(void);
+}
+
+void highPriorityTask(void *myData)
+{
+    printf("High priority task started and now looping for 10 seconds.  Our priority is %d.\n", uxTaskPriorityGet(nullptr));
+    TickType_t startTicks = xTaskGetTickCount();
+    while (xTaskGetTickCount() - startTicks < (10 * 1000 / portTICK_PERIOD_MS))
+    {
+        // Do nothing but loop
+    }
+    printf("High priority task ended\n");
+    vTaskDelete(nullptr);
+}
+
+void hardLoopTask(void *myData)
+{
+    printf("Hard loop task started ...\n");
+    while (1)
+    {
+        // do nothing but burn CPU
+    }
+}
+
+void hardLoopTaskNoInterrupts(void *myData)
+{
+    printf("Hard loop task disabling interrupts started ...\n");
+    taskDISABLE_INTERRUPTS();
+    while (1)
+    {
+        // do nothing but burn CPU
+    }
+}
+
+void myTask(void *myData)
+{
+    printf("# Running in myTask\n");
+    printf("# Registering our new task with the task watchdog.\n");
+    esp_task_wdt_add(nullptr);
+
+    printf("# Looping 5 times with a delay of 1 second and not feeding the watchdog.\n");
+    for (int i = 0; i < 5; i++)
+    {
+        vTaskDelay(1000 / portTICK_PERIOD_MS);
+        printf("Tick\n");
+    }
+
+    printf("# Looping 5 times with a delay of 1 second and positively feeding the watchdog.\n");
+    esp_task_wdt_reset();
+    for (int i = 0; i < 5; i++)
+    {
+        vTaskDelay(1000 / portTICK_PERIOD_MS);
+        printf("Tick\n");
+        esp_task_wdt_reset();
+    }
+
+    printf("# Removing our watchdog registration so we can do something expensive.\n");
+    esp_task_wdt_delete(nullptr);
+
+    printf("# Looping 5 times with a delay of 1 second and not feeding the watchdog.\n");
+    for (int i = 0; i < 5; i++)
+    {
+        vTaskDelay(1000 / portTICK_PERIOD_MS);
+        printf("Tick\n");
+    }
+
+    printf("# Re-registering our task with the task watchdog.\n");
+    esp_task_wdt_add(nullptr);
+    printf("# Looping 5 times with a delay of 1 second and not feeding the watchdog.\n");
+    for (int i = 0; i < 5; i++)
+    {
+        vTaskDelay(1000 / portTICK_PERIOD_MS);
+        printf("Tick\n");
+    }
+
+    printf("# Our current task priority is %d.\n", uxTaskPriorityGet(nullptr));
+    printf("# Spwaning a higher priority task\n");
+    xTaskCreate(highPriorityTask, // Task code
+                "Priority task",  // Name of task
+                16 * 1024,        // Stack size
+                nullptr,          // Task data
+                5,                // Priority
+                nullptr           // task handle
+    );
+
+    printf("# Looping 5 times with a delay of 1 second and positively feeding the watchdog.\n");
+    esp_task_wdt_reset();
+    for (int i = 0; i < 5; i++)
+    {
+        vTaskDelay(1000 / portTICK_PERIOD_MS);
+        printf("Tick\n");
+        esp_task_wdt_reset();
+    }
+
+    printf("Spawning a hard-loop function!\n");
+    xTaskCreate(hardLoopTaskNoInterrupts, // Task code
+                "Hard Loop",  // Name of task
+                16 * 1024,    // Stack size
+                nullptr,      // Task data
+                5,            // Priority
+                nullptr       // task handle
+    );
+
+    printf("# Looping 5 times with a delay of 1 second and positively feeding the watchdog.\n");
+    esp_task_wdt_reset();
+    for (int i = 0; i < 5; i++)
+    {
+        vTaskDelay(1000 / portTICK_PERIOD_MS);
+        printf("Tick\n");
+        esp_task_wdt_reset();
+    }
+
+
+    printf("# Removing our watchdog registration before we end the task.\n");
+    esp_task_wdt_delete(nullptr);
+
+    printf("# Ending myTask\n");
+    vTaskDelete(nullptr);
+} // myTask
+
+void app_main(void)
+{
+    xTaskHandle handle;
+    printf("App starting\n");
+    printf("Initializing the task watchdog subsystem with an interval of 2 seconds.\n");
+    esp_task_wdt_init(2, false);
+
+    printf("Creatign a new task.\n");
+    // Now let us create a new task.
+    xTaskCreate(myTask,    // Task code
+                "My Task", // Name of task
+                16 * 1024, // Stack size
+                nullptr,   // Task data
+                0,         // Priority
+                &handle    // task handle
+    );
+
+    //printf("App Ended!\n");
+} // app_main