Mbed EventQueue example 1: Ticker Callback and deferred printf()

main.cpp

// Execution of certain function in an ISR context is not safe. 
// For example, printf() in an interrupt context causes a Mutex error. 
// Using Mbed's EventQueue, you can defer execution of code from an interrupt context to a user context.
// More about EventQueue: https://os.mbed.com/docs/mbed-os/v5.15/tutorials/the-eventqueue-api.html

#include "mbed.h" 

Ticker ticker;
EventQueue *queue = mbed_event_queue(); // event queue
int counter = 0;

void processInUserContext() {
    printf("printing in a user context. counter = %d\r\n", counter);
}

void tickerCallback() {
    counter += 1;
    queue->call(&processInUserContext); // defer the execution to a different context
} 
 
int main() {
    ticker.attach(&tickerCallback, 1.0);       
    queue->dispatch_forever();
}