Mbed EventQueue example 3: Mbed OS6 UnbufferedSerial Interrupt Callback and deferred printf()

main.cpp

#include "mbed.h"
// EventQueue
EventQueue *queue = mbed_event_queue();

// Create a DigitalOutput object to toggle an LED whenever data is received.
static DigitalOut led(LED1);

// Create a UnbufferedSerial object with a default baud rate.
static UnbufferedSerial serial_port(USBTX, USBRX);

void process_in_user_context(char c) {
    printf("Printing in a user context. Received [%c].\r\n", c);
}

void on_rx_interrupt() {
    char c;

    // Toggle the LED.
    led = !led;

    // Read the data to clear the receive interrupt.
    if (serial_port.read(&c, 1)) {
        // defer the execution to a different context
        queue->call(&process_in_user_context, c);
    }
}

int main(void) {
    // Set desired properties (9600-8-N-1).
    serial_port.baud(9600);
    serial_port.format(
        /* bits */ 8,
        /* parity */ SerialBase::None,
        /* stop bit */ 1
    );

    // Register a callback to process a Rx (receive) interrupt.
    serial_port.attach(&on_rx_interrupt, SerialBase::RxIrq);
}