The demo tasks demonstrate basic use of FreeRTOS, with inter-task communication using queues and mutexes.
For details on how the demo works, see Introduction.
For detailed information on the tasks, see:
The demo tasks depend on the following drivers:
Functions | |
| static void | cdc_rx_handler (uint8_t instance) |
| Interrupt handler for reception from EDBG Virtual COM Port. More... | |
| void | demotasks_init (void) |
| Initialize tasks and resources for demo. More... | |
Variables | |
| bool volatile | tickless_enable |
| Global variable to control tickless operation. More... | |
Task configuration | |
| #define | UART_TASK_PRIORITY (tskIDLE_PRIORITY + 3) |
| #define | UART_TASK_DELAY (10 / portTICK_RATE_MS) |
| #define | MAIN_TASK_PRIORITY (tskIDLE_PRIORITY + 2) |
| #define | MAIN_TASK_DELAY (100 / portTICK_RATE_MS) |
| #define | GRAPH_TASK_PRIORITY (tskIDLE_PRIORITY + 1) |
| #define | GRAPH_TASK_DELAY (50 / portTICK_RATE_MS) |
| #define | TERMINAL_TASK_PRIORITY (tskIDLE_PRIORITY + 1) |
| #define | TERMINAL_TASK_DELAY (1000 / portTICK_RATE_MS) |
| #define | ABOUT_TASK_PRIORITY (tskIDLE_PRIORITY + 1) |
| #define | ABOUT_TASK_DELAY (33 / portTICK_RATE_MS) |
Menu and display configuration | |
| enum | menu_items { MENU_ITEM_GRAPH, MENU_ITEM_TERMINAL, MENU_ITEM_ABOUT, MENU_NUM_ITEMS, MENU_ITEM_GRAPH, MENU_ITEM_TERMINAL, MENU_ITEM_ABOUT, MENU_NUM_ITEMS } |
| Available selections in menu. More... | |
| #define | MENU_HEIGHT 8 |
| Height of menu bar. More... | |
| #define | MENU_ITEM_WIDTH (((GFX_MONO_LCD_WIDTH - (MENU_NUM_ITEMS - 1))) / MENU_NUM_ITEMS) |
| Width per menu item. More... | |
| #define | CANVAS_HEIGHT ((GFX_MONO_LCD_HEIGHT / 2) - (MENU_HEIGHT + 1)) |
| Height of area in which to draw content. More... | |
| #define | CANVAS_WIDTH (GFX_MONO_LCD_WIDTH) |
| Width of area in which to draw content. More... | |
| #define | CANVAS_GRAPH_Y_OFFSET (GFX_MONO_LCD_HEIGHT / 2) |
| Offset of Y-coordinate for display buffer of graph. More... | |
| #define | TERMINAL_LINES (1 + ((CANVAS_HEIGHT - SYSFONT_HEIGHT) / (SYSFONT_HEIGHT + 1))) |
| Character lines on display. More... | |
| #define | TERMINAL_COLUMNS (CANVAS_WIDTH / SYSFONT_WIDTH) |
| Character columns on display. More... | |
| #define | TERMINAL_BUFFER_LINES (1 + TERMINAL_LINES) |
| Character lines in terminal buffer. More... | |
| #define | TERMINAL_BUFFER_COLUMNS (1 + TERMINAL_COLUMNS) |
| Character columns in terminal buffer. More... | |
Global constants and variables | |
| static const char | menu_items_text [MENU_NUM_ITEMS][6] |
| Labels for menu items. More... | |
| static const char | about_text [] |
| Text to display on about screen when tickless operation is disabled. More... | |
| static const char | about_text_tickless [] |
| Text to display on about screen when tickless operation is enabled. More... | |
| static struct usart_module | cdc_usart |
| Instance for Embedded Debugger (EDBG) Virtual COM Port driver. More... | |
| static uint8_t | graph_noise = 128 |
| Pseudo-random noise for graph task. More... | |
| static uint8_t | terminal_buffer [TERMINAL_BUFFER_LINES][TERMINAL_BUFFER_COLUMNS] |
| Buffer for terminal text. More... | |
| static uint8_t | terminal_line_offset |
| Index of latest terminal line (first to be printed) More... | |
| static xQueueHandle | terminal_in_queue |
| Queue for incoming terminal characters. More... | |
| static xSemaphoreHandle | display_mutex |
| Semaphore to signal busy display. More... | |
| static xSemaphoreHandle | terminal_mutex |
| Semaphore to signal busy terminal buffer. More... | |
| static xTaskHandle | terminal_task_handle |
| Handle for terminal output task. More... | |
| static xTaskHandle | about_task_handle |
| Handle for about screen task. More... | |
| static | OLED1_CREATE_INSTANCE (oled1, OLED1_EXT_HEADER) |
| Instance for OLED1 Xplained Pro LED and button driver. More... | |
Tasks for demo | |
| static void | main_task (void *params) |
| Main demo task. More... | |
| static void | graph_task (void *params) |
| Graph task. More... | |
| static void | terminal_task (void *params) |
| Terminal task. More... | |
| static void | about_task (void *params) |
| About task. More... | |
| static void | uart_task (void *params) |
| UART task. More... | |
Task configuration | |
| #define | UART_TASK_PRIORITY (tskIDLE_PRIORITY + 3) |
| #define | UART_TASK_DELAY (10 / portTICK_RATE_MS) |
| #define | MAIN_TASK_PRIORITY (tskIDLE_PRIORITY + 2) |
| #define | MAIN_TASK_DELAY (100 / portTICK_RATE_MS) |
| #define | GRAPH_TASK_PRIORITY (tskIDLE_PRIORITY + 1) |
| #define | GRAPH_TASK_DELAY (50 / portTICK_RATE_MS) |
| #define | TERMINAL_TASK_PRIORITY (tskIDLE_PRIORITY + 1) |
| #define | TERMINAL_TASK_DELAY (1000 / portTICK_RATE_MS) |
| #define | ABOUT_TASK_PRIORITY (tskIDLE_PRIORITY + 1) |
| #define | ABOUT_TASK_DELAY (33 / portTICK_RATE_MS) |
Menu and display configuration | |
| enum | menu_items { MENU_ITEM_GRAPH, MENU_ITEM_TERMINAL, MENU_ITEM_ABOUT, MENU_NUM_ITEMS, MENU_ITEM_GRAPH, MENU_ITEM_TERMINAL, MENU_ITEM_ABOUT, MENU_NUM_ITEMS } |
| Available selections in menu. More... | |
| #define | MENU_HEIGHT 8 |
| Height of menu bar. More... | |
| #define | MENU_ITEM_WIDTH (((GFX_MONO_LCD_WIDTH - (MENU_NUM_ITEMS - 1))) / MENU_NUM_ITEMS) |
| Width per menu item. More... | |
| #define | CANVAS_HEIGHT ((GFX_MONO_LCD_HEIGHT / 2) - (MENU_HEIGHT + 1)) |
| Height of area in which to draw content. More... | |
| #define | CANVAS_WIDTH (GFX_MONO_LCD_WIDTH) |
| Width of area in which to draw content. More... | |
| #define | CANVAS_GRAPH_Y_OFFSET (GFX_MONO_LCD_HEIGHT / 2) |
| Offset of Y-coordinate for display buffer of graph. More... | |
| #define | TERMINAL_LINES (1 + ((CANVAS_HEIGHT - SYSFONT_HEIGHT) / (SYSFONT_HEIGHT + 1))) |
| Character lines on display. More... | |
| #define | TERMINAL_COLUMNS (CANVAS_WIDTH / SYSFONT_WIDTH) |
| Character columns on display. More... | |
| #define | TERMINAL_BUFFER_LINES (1 + TERMINAL_LINES) |
| Character lines in terminal buffer. More... | |
| #define | TERMINAL_BUFFER_COLUMNS (1 + TERMINAL_COLUMNS) |
| Character columns in terminal buffer. More... | |
Global constants and variables | |
| static const char | menu_items_text [MENU_NUM_ITEMS][6] |
| Labels for menu items. More... | |
| static const char | about_text [] |
| Text to display on about screen. More... | |
| static struct usart_module | cdc_usart |
| Instance for Embedded Debugger (EDBG) Virtual COM Port driver. More... | |
| static uint8_t | graph_noise = 128 |
| Pseudo-random noise for graph task. More... | |
| static uint8_t | terminal_buffer [TERMINAL_BUFFER_LINES][TERMINAL_BUFFER_COLUMNS] |
| Buffer for terminal text. More... | |
| static uint8_t | terminal_line_offset |
| Index of latest terminal line (first to be printed) More... | |
| static xQueueHandle | terminal_in_queue |
| Queue for incoming terminal characters. More... | |
| static xSemaphoreHandle | display_mutex |
| Semaphore to signal busy display. More... | |
| static xSemaphoreHandle | terminal_mutex |
| Semaphore to signal busy terminal buffer. More... | |
| static xTaskHandle | terminal_task_handle |
| Handle for terminal output task. More... | |
| static xTaskHandle | about_task_handle |
| Handle for about screen task. More... | |
| #define ABOUT_TASK_DELAY (33 / portTICK_RATE_MS) |
Referenced by about_task().
| #define ABOUT_TASK_DELAY (33 / portTICK_RATE_MS) |
Referenced by about_task().
| #define ABOUT_TASK_PRIORITY (tskIDLE_PRIORITY + 1) |
Referenced by demotasks_init().
| #define ABOUT_TASK_PRIORITY (tskIDLE_PRIORITY + 1) |
| #define CANVAS_GRAPH_Y_OFFSET (GFX_MONO_LCD_HEIGHT / 2) |
Offset of Y-coordinate for display buffer of graph.
Referenced by graph_task(), and main_task().
| #define CANVAS_GRAPH_Y_OFFSET (GFX_MONO_LCD_HEIGHT / 2) |
Offset of Y-coordinate for display buffer of graph.
Referenced by graph_task(), and main_task().
| #define CANVAS_HEIGHT ((GFX_MONO_LCD_HEIGHT / 2) - (MENU_HEIGHT + 1)) |
Height of area in which to draw content.
Referenced by about_task(), graph_task(), and main_task().
| #define CANVAS_HEIGHT ((GFX_MONO_LCD_HEIGHT / 2) - (MENU_HEIGHT + 1)) |
Height of area in which to draw content.
Referenced by about_task(), graph_task(), and main_task().
| #define CANVAS_WIDTH (GFX_MONO_LCD_WIDTH) |
Width of area in which to draw content.
Referenced by about_task(), graph_task(), and terminal_task().
| #define CANVAS_WIDTH (GFX_MONO_LCD_WIDTH) |
Width of area in which to draw content.
Referenced by about_task(), graph_task(), and terminal_task().
| #define GRAPH_TASK_DELAY (50 / portTICK_RATE_MS) |
Referenced by graph_task().
| #define GRAPH_TASK_DELAY (50 / portTICK_RATE_MS) |
Referenced by graph_task().
| #define GRAPH_TASK_PRIORITY (tskIDLE_PRIORITY + 1) |
Referenced by demotasks_init().
| #define GRAPH_TASK_PRIORITY (tskIDLE_PRIORITY + 1) |
| #define MAIN_TASK_DELAY (100 / portTICK_RATE_MS) |
Referenced by main_task().
| #define MAIN_TASK_DELAY (100 / portTICK_RATE_MS) |
Referenced by main_task().
| #define MAIN_TASK_PRIORITY (tskIDLE_PRIORITY + 2) |
Referenced by demotasks_init().
| #define MAIN_TASK_PRIORITY (tskIDLE_PRIORITY + 2) |
| #define MENU_HEIGHT 8 |
Height of menu bar.
Referenced by main_task().
| #define MENU_HEIGHT 8 |
Height of menu bar.
Referenced by main_task().
| #define MENU_ITEM_WIDTH (((GFX_MONO_LCD_WIDTH - (MENU_NUM_ITEMS - 1))) / MENU_NUM_ITEMS) |
Width per menu item.
Referenced by main_task().
| #define MENU_ITEM_WIDTH (((GFX_MONO_LCD_WIDTH - (MENU_NUM_ITEMS - 1))) / MENU_NUM_ITEMS) |
Width per menu item.
Referenced by main_task().
| #define TERMINAL_BUFFER_COLUMNS (1 + TERMINAL_COLUMNS) |
Character columns in terminal buffer.
| #define TERMINAL_BUFFER_COLUMNS (1 + TERMINAL_COLUMNS) |
Character columns in terminal buffer.
| #define TERMINAL_BUFFER_LINES (1 + TERMINAL_LINES) |
Character lines in terminal buffer.
Referenced by terminal_task(), and uart_task().
| #define TERMINAL_BUFFER_LINES (1 + TERMINAL_LINES) |
Character lines in terminal buffer.
Referenced by terminal_task(), and uart_task().
| #define TERMINAL_COLUMNS (CANVAS_WIDTH / SYSFONT_WIDTH) |
Character columns on display.
Referenced by about_task(), terminal_task(), and uart_task().
| #define TERMINAL_COLUMNS (CANVAS_WIDTH / SYSFONT_WIDTH) |
Character columns on display.
Referenced by about_task(), terminal_task(), and uart_task().
| #define TERMINAL_LINES (1 + ((CANVAS_HEIGHT - SYSFONT_HEIGHT) / (SYSFONT_HEIGHT + 1))) |
Character lines on display.
Referenced by terminal_task().
| #define TERMINAL_LINES (1 + ((CANVAS_HEIGHT - SYSFONT_HEIGHT) / (SYSFONT_HEIGHT + 1))) |
Character lines on display.
Referenced by terminal_task().
| #define TERMINAL_TASK_DELAY (1000 / portTICK_RATE_MS) |
Referenced by terminal_task().
| #define TERMINAL_TASK_DELAY (1000 / portTICK_RATE_MS) |
Referenced by terminal_task().
| #define TERMINAL_TASK_PRIORITY (tskIDLE_PRIORITY + 1) |
| #define TERMINAL_TASK_PRIORITY (tskIDLE_PRIORITY + 1) |
Referenced by demotasks_init().
| #define UART_TASK_DELAY (10 / portTICK_RATE_MS) |
Referenced by uart_task().
| #define UART_TASK_DELAY (10 / portTICK_RATE_MS) |
Referenced by uart_task().
| #define UART_TASK_PRIORITY (tskIDLE_PRIORITY + 3) |
Referenced by demotasks_init().
| #define UART_TASK_PRIORITY (tskIDLE_PRIORITY + 3) |
| enum menu_items |
| enum menu_items |
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About task.
This task prints a short text about the demo, with a simple zooming animation.
| params | Parameters for the task. (Not used.) |
References ABOUT_TASK_DELAY, about_text, about_text_tickless, CANVAS_HEIGHT, CANVAS_WIDTH, display_mutex, gfx_mono_draw_char(), i, NULL, OLED1_LED2_ID, oled1_set_led_state(), sysfont, TERMINAL_COLUMNS, tickless_enable, vTaskDelay(), vTaskSuspend(), xSemaphoreGive, and xSemaphoreTake.
Referenced by demotasks_init().
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Interrupt handler for reception from EDBG Virtual COM Port.
UART interrupt handler for reception on EDBG CDC UART.
This function is based on the interrupt handler of the SERCOM USART callback driver (_usart_interrupt_handler()). It has been modified to only handle the receive interrupt and to push the received data directly into the queue for terminal characters (terminal_in_queue), and echo the character back to the sender.
| instance | Instance number of SERCOM that generated interrupt. |
References data, NULL, terminal_in_queue, and xQueueSendFromISR.
Referenced by demotasks_init().
| void demotasks_init | ( | void | ) |
Initialize tasks and resources for demo.
This function initializes the OLED1 Xplained Pro LED and button driver instance and the Embedded Debugger (EDBG) Virtual COM Port driver instance for reception, then creates all the objects for FreeRTOS to run the demo.
References about_task(), about_task_handle, ABOUT_TASK_PRIORITY, cdc_rx_handler(), cdc_rx_init(), cdc_usart, display_mutex, graph_task(), GRAPH_TASK_PRIORITY, main_task(), MAIN_TASK_PRIORITY, NULL, oled1_init(), terminal_in_queue, terminal_mutex, terminal_task(), terminal_task_handle, TERMINAL_TASK_PRIORITY, uart_task(), UART_TASK_PRIORITY, vTaskSuspend(), xQueueCreate, xSemaphoreCreateMutex, and xTaskCreate.
Referenced by main().
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Graph task.
This task runs in the background to draw a pseudo-random graph to a dedicated display buffer. If the user selects a different screen than the graph, it will continue to update even though it is not visible until the graph screen is selected again.
| params | Parameters for the task. (Not used.) |
References CANVAS_GRAPH_Y_OFFSET, CANVAS_HEIGHT, CANVAS_WIDTH, display_mutex, gfx_mono_draw_line, gfx_mono_draw_pixel, gfx_mono_draw_vertical_line, GFX_PIXEL_CLR, GFX_PIXEL_SET, graph_noise, GRAPH_TASK_DELAY, OLED1_LED1_ID, oled1_set_led_state(), vTaskDelay(), xSemaphoreGive, and xSemaphoreTake.
Referenced by demotasks_init().
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Main demo task.
This task keeps track of which screen the user has selected, which tasks to resume/suspend to draw the selected screen, and also draws the menu bar.
The menu bar shows which screens the user can select by clicking the corresponding buttons on the OLED1 Xplained Pro:
| params | Parameters for the task. (Not used.) |
References about_task_handle, CANVAS_GRAPH_Y_OFFSET, CANVAS_HEIGHT, display_mutex, gfx_mono_draw_filled_rect, gfx_mono_draw_horizontal_line, gfx_mono_draw_rect, gfx_mono_draw_string(), gfx_mono_draw_vertical_line, GFX_MONO_LCD_HEIGHT, GFX_MONO_LCD_WIDTH, GFX_PIXEL_CLR, GFX_PIXEL_SET, i, MAIN_TASK_DELAY, MENU_HEIGHT, MENU_ITEM_ABOUT, MENU_ITEM_GRAPH, MENU_ITEM_TERMINAL, MENU_ITEM_WIDTH, menu_items_text, MENU_NUM_ITEMS, NULL, OLED1_BUTTON1_ID, OLED1_BUTTON2_ID, OLED1_BUTTON3_ID, oled1_get_button_state(), OLED1_LED3_ID, oled1_set_led_state(), ssd1306_set_display_start_line_address(), sysfont, terminal_task_handle, vTaskDelay(), vTaskResume(), vTaskSuspend(), xSemaphoreGive, and xSemaphoreTake.
Referenced by demotasks_init().
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Instance for OLED1 Xplained Pro LED and button driver.
The extension header to use is configured with OLED1_EXT_HEADER.
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Terminal task.
This task prints the terminal text buffer to the display.
| params | Parameters for the task. (Not used.) |
References CANVAS_WIDTH, display_mutex, gfx_mono_draw_char(), gfx_mono_draw_filled_rect, GFX_PIXEL_CLR, OLED1_LED2_ID, oled1_set_led_state(), sysfont, terminal_buffer, TERMINAL_BUFFER_LINES, TERMINAL_COLUMNS, terminal_line_offset, TERMINAL_LINES, terminal_mutex, TERMINAL_TASK_DELAY, vTaskDelay(), xSemaphoreGive, and xSemaphoreTake.
Referenced by demotasks_init().
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UART task.
This task runs in the background to handle the queued, incoming terminal characters and write them to the terminal text buffer. It does not print anything to the display – that is done by terminal_task().
| params | Parameters for the task. (Not used.) |
References OLED1_LED1_ID, oled1_set_led_state(), terminal_buffer, TERMINAL_BUFFER_LINES, TERMINAL_COLUMNS, terminal_in_queue, terminal_line_offset, terminal_mutex, UART_TASK_DELAY, vTaskDelay(), xQueueReceive, xSemaphoreGive, and xSemaphoreTake.
Referenced by demotasks_init().
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Handle for about screen task.
Referenced by main_task().
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Handle for about screen task.
Referenced by demotasks_init(), and main_task().
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Text to display on about screen when tickless operation is disabled.
Referenced by about_task().
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Text to display on about screen.
Referenced by about_task().
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Text to display on about screen when tickless operation is enabled.
Referenced by about_task().
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Instance for Embedded Debugger (EDBG) Virtual COM Port driver.
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Instance for Embedded Debugger (EDBG) Virtual COM Port driver.
Referenced by demotasks_init().
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Semaphore to signal busy display.
Referenced by about_task(), graph_task(), main_task(), and terminal_task().
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Semaphore to signal busy display.
Referenced by about_task(), demotasks_init(), graph_task(), main_task(), and terminal_task().
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Pseudo-random noise for graph task.
Referenced by graph_task().
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Pseudo-random noise for graph task.
Referenced by graph_task().
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Buffer for terminal text.
Referenced by terminal_task(), and uart_task().
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Buffer for terminal text.
Referenced by terminal_task(), and uart_task().
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Queue for incoming terminal characters.
Referenced by cdc_rx_handler(), and uart_task().
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Queue for incoming terminal characters.
Referenced by cdc_rx_handler(), demotasks_init(), and uart_task().
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Index of latest terminal line (first to be printed)
Referenced by terminal_task(), and uart_task().
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Index of latest terminal line (first to be printed)
Referenced by terminal_task(), and uart_task().
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Semaphore to signal busy terminal buffer.
Referenced by terminal_task(), and uart_task().
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Semaphore to signal busy terminal buffer.
Referenced by demotasks_init(), terminal_task(), and uart_task().
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Handle for terminal output task.
Referenced by main_task().
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Handle for terminal output task.
Referenced by demotasks_init(), and main_task().
| bool volatile tickless_enable |
Global variable to control tickless operation.
Referenced by about_task(), and vPortSuppressTicksAndSleep().
1.8.5