The current scheduler library supports esp8266 Arduino core '2.6.3'.
Apply the path core_esp8266_2.6.3.patch for esp8266 Arduino core '2.6.3'. First, unpack git repository to the home directory and then apply the patch into the current availabe esp8266 core. Currently, the esp8266 core is available at ~/.arduino15. Use the following commands to apply the path and adapt them accordingly if needed.
cd ~
git clone https://github.com/anmaped/esp8266-scheduler.git
cd ~/.arduino15/packages/esp8266/hardware/esp8266/
patch -s -p0 < ~/esp8266-scheduler/libraries/scheduler/core_esp8266_2.6.3.patch
We have to chose the Arduino 1.6.8 with esp8266 core version 2.3.0. This patched runtime is available in https://github.com/srmq/Arduino/tree/scheduler_branch. The Arduino 1.6.8 for windows is availalbe in https://www.arduino.cc/download_handler.php?f=/arduino-1.6.8-windows.zip and for Linux 32 in https://www.arduino.cc/download_handler.php?f=/arduino-1.6.8-linux32.tar.xz.
Instructions: Replace the esp8266 core inside the Arduino folder ~/.arduino15/packages/esp8266/hardware with the patched version provided in the branch above.
- Install esp8266 2.3.0 using the usual arduino esp8266 instructions (add http://arduino.esp8266.com/stable/package_esp8266com_index.json to preferences, and install it using the board manager).
- Create the folder 'hardware/esp8266com/esp8266' and extract inside it the content available in the branch
https://github.com/srmq/Arduino/tree/scheduler_branch. Simply download the zip file from GitHub and rename it locally. - Add the Scheduler library to Arduino.
Note that the esp8266 core will replace the installed version 2.3.0.
This library implements an extended sub-set of the Arduino Scheduler class. Multiple loop() functions, tasks, may be started and run in a collaborative multi-tasking style. The tasks are run until they call yield() or delay(). The Arduino yield() function is replaced by an implementation in the library that allows context switching.
Tasks should be viewed as static and continuous. This implementation does not allocate tasks on the heap. They are allocated on the normal stack and linked into a cyclic run queue. One-shot tasks are not supported. Instead the task start function is extended with a setup function reference. Tasks are started with:
Scheduler.start(taskSetup, taskLoop [,taskStackSize]).
The tasks will start execution when the main task yields. The taskSetup is called first and once by the task followed by repeated calls to taskLoop. This works just as the Arduino setup() and loop() functions. There is also an optional parameter, taskStackSize. The default value depends on the architecture (128 bytes for AVR and 512 bytes for SAM/SAMD/Teensy 3.1).
The Scheduler is a single-ton and the library creates the single instance.
This library also includes support for task synchronization and communication; Semaphores, Queues and Channels.
Download and unzip the esp8266-scheduler library into your sketchbook libraries directory. Rename from esp8266-scheduler-master to esp8266-scheduler.
The Scheduler library and examples should be found in the Arduino IDE File>Examples menu.
There are several benchmark sketches in the examples directory. Below are some of the results.
| Board | us | cycles |
|---|---|---|
| Arduino Mega 2560 (16 MHz) | 12.64 | 203 |
| Arduino Uno, Nano, Pro-Mini, etc (16 MHz) | 11.00 | 176 |
| Sparkfun SAMD21 (48 MHz) | 2.60 | 125 |
| Arduino Due (84 MHz) | 1.36 | 115 |
| Teensy 3.1 (72 MHz) | 1.10 | 80 |
| Board | Tasks | Stack (bytes) |
|---|---|---|
| Arduino Uno, Nano, Pro-Mini, etc (16 MHz) | 9 | 128 |
| Sparkfun SAMD21 (48 MHz) | 26 | 512 |
| Teensy 3.1 (72 MHz) | 26 | 512 |
| Arduino Mega 2560 (16 MHz) | 48 | 128 |
| Arduino Due (84 MHz) | 52 | 512 |
| Board | PROGMEM | SRAM (bytes) |
|---|---|---|
| Arduino Due (84 MHz) | 224 | NA |
| Arduino Uno, Nano, Pro-Mini, etc (16 MHz) | 546 | 42 |
| Arduino Mega 2560 (16 MHz) | 548 | 44 |
| Sparkfun SAMD21 (48 MHz) | NA | NA |
| Teensy 3.1 (72 MHz) | NA | NA |