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85 lines
3.1 KiB
ReStructuredText
85 lines
3.1 KiB
ReStructuredText
System Tasks
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************
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This document explains the ESP8266 RTOS SDK internal system tasks.
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Overview
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========
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The main tasks and their attributes are as following:
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+-------------------------+----------------+----------------+
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| Names | stack size | Priority |
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+=========================+================+================+
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| uiT | 3584(C) | 14 |
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+-------------------------+----------------+----------------+
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| IDLE | 768 | 0 |
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+-------------------------+----------------+----------------+
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| Tmr | 2048(C) | 2 |
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+-------------------------+----------------+----------------+
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| ppT | 2048(C) | 13 |
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+-------------------------+----------------+----------------+
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| pmT | 1024 | 11 |
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+-------------------------+----------------+----------------+
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| rtT | 2048 | 12 |
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+-------------------------+----------------+----------------+
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| tiT | 2048(C) | 8 |
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+-------------------------+----------------+----------------+
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| esp_event_loop_task | 2048(C) | 10 |
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+-------------------------+----------------+----------------+
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Note: (C) means it is configurable by "menuconfig".
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Tasks Introduction
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==================
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uiT
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---
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This task initializes the system, including peripherals, file system, user entry function and so on.
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This task will delete itself and free the resources after calling `app_main`.
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IDLE
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----
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This task is freeRTOS internal idle callback task, it is created when starting the freeRTOS.
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Its hook function is `vApplicationIdleHook`.
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The system's function of `sleep` and function of feeding `task watch dog` are called in the `vApplicationIdleHook`.
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Tmr
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---
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This task is the processor of freeRTOS internal software timer.
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ppT
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---
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This task is to process Wi-Fi hardware driver and stack. It posts messages from the logic link layer to the upper layer TCP/IP stack after transforming them into ethernet packets.
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pmT
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---
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The task is for system power management. It will check if the system can sleep right now, and if it is, it will start preparing for system sleep.
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rtT
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---
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The task is the processor of high priority hardware timer. It mainly process Wi-Fi real time events.
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It is suggested that functions based on this component should not be called in application, because it may block other low layer Wi-Fi functions.
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tiT
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---
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The task is the main task of TCP-IP stack(LwIP) , it is to deal with TCP-IP packets.
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esp_event_loop_task
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-------------------
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The task processes system events, for example, Wi-Fi and TCP-IP stack events.
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Suggestions
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===========
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In general, the priority of user task should NOT be higher than the system real timer task's priority (12). So it is suggested that keep your user tasks' priorities less than 12.
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If you want to speed up the TCP/UDP throughput, you can try to set the priority of send/receive task to be higher than the "tiT" task's priority (8).
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