/* * FreeRTOS Kernel V10.3.0 * Copyright (C) 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved. * * Permission is hereby granted, free of charge, to any person obtaining a copy of * this software and associated documentation files (the "Software"), to deal in * the Software without restriction, including without limitation the rights to * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of * the Software, and to permit persons to whom the Software is furnished to do so, * subject to the following conditions: * * The above copyright notice and this permission notice shall be included in all * copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. * * http://www.FreeRTOS.org * http://aws.amazon.com/freertos * * 1 tab == 4 spaces! */ /* This simple demo project runs on the STM32 Discovery board, which is populated with an STM32F100RB Cortex-M3 microcontroller. The discovery board makes an ideal low cost evaluation platform, but the 8K of RAM provided on the STM32F100RB does not allow the simple application to demonstrate all of all the FreeRTOS kernel features. Therefore, this simple demo only actively demonstrates task, queue, timer and interrupt functionality. In addition, the demo is configured to include malloc failure, idle and stack overflow hook functions. The idle hook function: The idle hook function queries the amount of FreeRTOS heap space that is remaining (see vApplicationIdleHook() defined in this file). The demo application is configured to use 7K of the available 8K of RAM as the FreeRTOS heap. Memory is only allocated from this heap during initialisation, and this demo only actually uses 1.6K bytes of the configured 7K available - leaving 5.4K bytes of heap space unallocated. The main() Function: main() creates one software timer, one queue, and two tasks. It then starts the scheduler. The Queue Send Task: The queue send task is implemented by the prvQueueSendTask() function in this file. prvQueueSendTask() sits in a loop that causes it to repeatedly block for 200 milliseconds, before sending the value 100 to the queue that was created within main(). Once the value is sent, the task loops back around to block for another 200 milliseconds. The Queue Receive Task: The queue receive task is implemented by the prvQueueReceiveTask() function in this file. prvQueueReceiveTask() sits in a loop where it repeatedly blocks on attempts to read data from the queue that was created within main(). When data is received, the task checks the value of the data, and if the value equals the expected 100, toggles the green LED. The 'block time' parameter passed to the queue receive function specifies that the task should be held in the Blocked state indefinitely to wait for data to be available on the queue. The queue receive task will only leave the Blocked state when the queue send task writes to the queue. As the queue send task writes to the queue every 200 milliseconds, the queue receive task leaves the Blocked state every 200 milliseconds, and therefore toggles the green LED every 200 milliseconds. The LED Software Timer and the Button Interrupt: The user button B1 is configured to generate an interrupt each time it is pressed. The interrupt service routine switches the red LED on, and resets the LED software timer. The LED timer has a 5000 millisecond (5 second) period, and uses a callback function that is defined to just turn the red LED off. Therefore, pressing the user button will turn the red LED on, and the LED will remain on until a full five seconds pass without the button being pressed. */ /* Kernel includes. */ #include "FreeRTOS.h" #include "task.h" #include "queue.h" #include "timers.h" /* STM32 Library includes. */ #include "stm32f10x.h" #include "STM32vldiscovery.h" /* Priorities at which the tasks are created. */ #define mainQUEUE_RECEIVE_TASK_PRIORITY ( tskIDLE_PRIORITY + 2 ) #define mainQUEUE_SEND_TASK_PRIORITY ( tskIDLE_PRIORITY + 1 ) /* The rate at which data is sent to the queue, specified in milliseconds, and converted to ticks using the portTICK_PERIOD_MS constant. */ #define mainQUEUE_SEND_FREQUENCY_MS ( 200 / portTICK_PERIOD_MS ) /* The number of items the queue can hold. This is 1 as the receive task will remove items as they are added, meaning the send task should always find the queue empty. */ #define mainQUEUE_LENGTH ( 1 ) /*-----------------------------------------------------------*/ /* * Setup the NVIC, LED outputs, and button inputs. */ static void prvSetupHardware( void ); /* * The tasks as described in the comments at the top of this file. */ static void prvQueueReceiveTask( void *pvParameters ); static void prvQueueSendTask( void *pvParameters ); /* * The LED timer callback function. This does nothing but switch the red LED * off. */ static void vLEDTimerCallback( TimerHandle_t xTimer ); /*-----------------------------------------------------------*/ /* The queue used by both tasks. */ static QueueHandle_t xQueue = NULL; /* The LED software timer. This uses vLEDTimerCallback() as its callback * function. */ static TimerHandle_t xLEDTimer = NULL; /*-----------------------------------------------------------*/ int main(void) { /* Configure the NVIC, LED outputs and button inputs. */ prvSetupHardware(); /* Create the queue. */ xQueue = xQueueCreate( mainQUEUE_LENGTH, sizeof( unsigned long ) ); if( xQueue != NULL ) { /* Start the two tasks as described in the comments at the top of this file. */ xTaskCreate( prvQueueReceiveTask, "Rx", configMINIMAL_STACK_SIZE, NULL, mainQUEUE_RECEIVE_TASK_PRIORITY, NULL ); xTaskCreate( prvQueueSendTask, "TX", configMINIMAL_STACK_SIZE, NULL, mainQUEUE_SEND_TASK_PRIORITY, NULL ); /* Create the software timer that is responsible for turning off the LED if the button is not pushed within 5000ms, as described at the top of this file. */ xLEDTimer = xTimerCreate( "LEDTimer", /* A text name, purely to help debugging. */ ( 5000 / portTICK_PERIOD_MS ),/* The timer period, in this case 5000ms (5s). */ pdFALSE, /* This is a one-shot timer, so xAutoReload is set to pdFALSE. */ ( void * ) 0, /* The ID is not used, so can be set to anything. */ vLEDTimerCallback /* The callback function that switches the LED off. */ ); /* Start the tasks and timer running. */ vTaskStartScheduler(); } /* If all is well, the scheduler will now be running, and the following line will never be reached. If the following line does execute, then there was insufficient FreeRTOS heap memory available for the idle and/or timer tasks to be created. See the memory management section on the FreeRTOS web site for more details. */ for( ;; ); } /*-----------------------------------------------------------*/ static void vLEDTimerCallback( TimerHandle_t xTimer ) { /* The timer has expired - so no button pushes have occurred in the last five seconds - turn the LED off. NOTE - accessing the LED port should use a critical section because it is accessed from multiple tasks, and the button interrupt - in this trivial case, for simplicity, the critical section is omitted. */ STM32vldiscovery_LEDOff( LED4 ); } /*-----------------------------------------------------------*/ /* The ISR executed when the user button is pushed. */ void EXTI0_IRQHandler( void ) { portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE; /* The button was pushed, so ensure the LED is on before resetting the LED timer. The LED timer will turn the LED off if the button is not pushed within 5000ms. */ STM32vldiscovery_LEDOn( LED4 ); /* This interrupt safe FreeRTOS function can be called from this interrupt because the interrupt priority is below the configMAX_SYSCALL_INTERRUPT_PRIORITY setting in FreeRTOSConfig.h. */ xTimerResetFromISR( xLEDTimer, &xHigherPriorityTaskWoken ); /* Clear the interrupt before leaving. */ EXTI_ClearITPendingBit( EXTI_Line0 ); /* If calling xTimerResetFromISR() caused a task (in this case the timer service/daemon task) to unblock, and the unblocked task has a priority higher than or equal to the task that was interrupted, then xHigherPriorityTaskWoken will now be set to pdTRUE, and calling portEND_SWITCHING_ISR() will ensure the unblocked task runs next. */ portEND_SWITCHING_ISR( xHigherPriorityTaskWoken ); } /*-----------------------------------------------------------*/ static void prvQueueSendTask( void *pvParameters ) { TickType_t xNextWakeTime; const unsigned long ulValueToSend = 100UL; /* Initialise xNextWakeTime - this only needs to be done once. */ xNextWakeTime = xTaskGetTickCount(); for( ;; ) { /* Place this task in the blocked state until it is time to run again. The block time is specified in ticks, the constant used converts ticks to ms. While in the Blocked state this task will not consume any CPU time. */ vTaskDelayUntil( &xNextWakeTime, mainQUEUE_SEND_FREQUENCY_MS ); /* Send to the queue - causing the queue receive task to unblock and toggle an LED. 0 is used as the block time so the sending operation will not block - it shouldn't need to block as the queue should always be empty at this point in the code. */ xQueueSend( xQueue, &ulValueToSend, 0 ); } } /*-----------------------------------------------------------*/ static void prvQueueReceiveTask( void *pvParameters ) { unsigned long ulReceivedValue; for( ;; ) { /* Wait until something arrives in the queue - this task will block indefinitely provided INCLUDE_vTaskSuspend is set to 1 in FreeRTOSConfig.h. */ xQueueReceive( xQueue, &ulReceivedValue, portMAX_DELAY ); /* To get here something must have been received from the queue, but is it the expected value? If it is, toggle the green LED. */ if( ulReceivedValue == 100UL ) { /* NOTE - accessing the LED port should use a critical section because it is accessed from multiple tasks, and the button interrupt - in this trivial case, for simplicity, the critical section is omitted. */ STM32vldiscovery_LEDToggle( LED3 ); } } } /*-----------------------------------------------------------*/ static void prvSetupHardware( void ) { /* Ensure that all 4 interrupt priority bits are used as the pre-emption priority. */ NVIC_PriorityGroupConfig( NVIC_PriorityGroup_4 ); /* Set up the LED outputs and the button inputs. */ STM32vldiscovery_LEDInit( LED3 ); STM32vldiscovery_LEDInit( LED4 ); STM32vldiscovery_PBInit( BUTTON_USER, BUTTON_MODE_EXTI ); /* Start with the LEDs off. */ STM32vldiscovery_LEDOff( LED3 ); STM32vldiscovery_LEDOff( LED4 ); } /*-----------------------------------------------------------*/ void vApplicationMallocFailedHook( void ) { /* Called if a call to pvPortMalloc() fails because there is insufficient free memory available in the FreeRTOS heap. pvPortMalloc() is called internally by FreeRTOS API functions that create tasks, queues, software timers, and semaphores. The size of the FreeRTOS heap is set by the configTOTAL_HEAP_SIZE configuration constant in FreeRTOSConfig.h. */ for( ;; ); } /*-----------------------------------------------------------*/ void vApplicationStackOverflowHook( TaskHandle_t pxTask, char *pcTaskName ) { ( void ) pcTaskName; ( void ) pxTask; /* Run time stack overflow checking is performed if configconfigCHECK_FOR_STACK_OVERFLOW is defined to 1 or 2. This hook function is called if a stack overflow is detected. */ for( ;; ); } /*-----------------------------------------------------------*/ void vApplicationIdleHook( void ) { volatile size_t xFreeStackSpace; /* This function is called on each cycle of the idle task. In this case it does nothing useful, other than report the amout of FreeRTOS heap that remains unallocated. */ xFreeStackSpace = xPortGetFreeHeapSize(); if( xFreeStackSpace > 100 ) { /* By now, the kernel has allocated everything it is going to, so if there is a lot of heap remaining unallocated then the value of configTOTAL_HEAP_SIZE in FreeRTOSConfig.h can be reduced accordingly. */ } }