In current configuration, the timer task (the one from FreeRTOS) has …

…the lowest priority (0). Both display and system tasks are also set on priority 0.

In cases where any other task takes too much time to execute (it can happen in Display Task, see InfiniTimeOrg/InfiniTime#825), the timer task does not have the opportunity to run fast enough to detect and debounce presses on the button.

This commit sets the following priorities:
 - [0] : Display  Task
 - [1] : Timer and System tasks
 - [2] : BLE Host
 - [3] : BLE LL

This way, we ensure that button presses will always be detected, even if the rendering of the display takes a huge amount of time.

src/FreeRTOSConfig.h

@@ -60,7 +60,7 @@
 #define configUSE_TICKLESS_IDLE_SIMPLE_DEBUG    0 /* See into vPortSuppressTicksAndSleep source code for explanation */
 #define configCPU_CLOCK_HZ                      (SystemCoreClock)
 #define configTICK_RATE_HZ                      1024
-#define configMAX_PRIORITIES                    (3)
+#define configMAX_PRIORITIES                    (4)
 #define configMINIMAL_STACK_SIZE                (120)
 #define configTOTAL_HEAP_SIZE                   (1024 * 17)
 #define configMAX_TASK_NAME_LEN                 (4)
@@ -93,7 +93,7 @@
 
 /* Software timer definitions. */
 #define configUSE_TIMERS             1
-#define configTIMER_TASK_PRIORITY    (0)
+#define configTIMER_TASK_PRIORITY    (1)
 #define configTIMER_QUEUE_LENGTH     32
 #define configTIMER_TASK_STACK_DEPTH (300)
 

src/systemtask/SystemTask.cpp

@@ -107,7 +107,7 @@ SystemTask::SystemTask(Drivers::SpiMaster& spi,
 
 void SystemTask::Start() {
   systemTasksMsgQueue = xQueueCreate(10, 1);
-  if (pdPASS != xTaskCreate(SystemTask::Process, "MAIN", 350, this, 0, &taskHandle)) {
+  if (pdPASS != xTaskCreate(SystemTask::Process, "MAIN", 350, this, 1, &taskHandle)) {
     APP_ERROR_HANDLER(NRF_ERROR_NO_MEM);
   }
 }