Protothreading/ Multithreading on Arduino Uno

Question

I am trying to use protothreads on Arduino Uno. I am following https://techtutorialsx.com/2017/12/30/esp32-arduino-using-the-pthreads-library/ .

I have downloaded the pthread.h header file and put it in the same directory as my .ino file.

I have changed the #include statement from the tutorial to #include "pthread.h" as the file is present in the same directory as my .ino file.

I am getting the following error:

Protothreading_example:11:4: error: 'pthread_t' was not declared in this scope
    pthread_t threads[4];
    ^
Protothreading_example:16:37: error: 'threads' was not declared in this scope
       returnValue = pthread_create(&threads[i], NULL, printThreadId, (void *)i);
                                     ^
Protothreading_example:16:79: error: 'pthread_create' was not declared in this scope
       returnValue = pthread_create(&threads[i], NULL, printThreadId, (void *)i);
                                                                               ^
exit status 1
'pthread_t' was not declared in this scope

I have two follow up questions:

1) Is there a better tutorial source for protothreading on Arduino?

2) I need to read data from multiple sensors and process separately. Since Arduino does not support multithreading at the hardware level, I have made another implementation to loop through an array of function pointers with a timer. Is this approach the same as protothreading?

Answer 1

The tutorial you mentioned is intended for ESP32, which has a different Arduino core than the Arduino Uno itself. Primarily it contains FreeRTOS, which supplies the underlying mechanisms for this library. It will not work with Arduino Uno as is.

I believe that you do not need multithreading for your application. You can just loop through the sensor readings and process it in the end of your loop. A step forward to concurrency would be to use a simple scheduler .