Minar depends on RTC

[tibmanus]

Environment
Board: FRDM-K64F

Steps to reproduce:
Schedule a change in the RTC time using the rtc_write (from rtc_api.h). Eg. set the RTC time to a higher value than the current one.

Actual behaviour:
The scheduler executes all the scheduled tasks as if the time actually would have elapsed.

Expected behaviour:
The scheduler depends solely on the ever increasing hardware clock (ticks), not on the real-time clock.

Please see attached code. Try to modify tmp_time += 20; to other values. Examine both LED and serial print behaviour. app_start.cpp
Yotta config:
"dependencies": {
"mbed-drivers": "^1.1.3"
}

[ciarmcom]

ARM Internal Ref: IOTSFW-2352

[0xc0170]

Thanks for reporting. Minar depends on lp ticker which is low power ticker. It can be RTC or any other timer. This bug is related to lp tickers which are using RTC. To quick fix for this, we could disable rtc_write() once lp ticker takes ownership of it. A proper fix, as we already did once and failed 😭 - our proposal to exactly fix this was ARMmbed/mbed-drivers#55, which was reverted later due to some problems with other dependencies.

I'll attach your code here:

#include "mbed-drivers/mbed.h"
#include "mbed-hal/rtc_api.h"

void blinky(void) {
    static DigitalOut led(LED_GREEN);
    led = !led;
}

void print_time(void) {
    time_t tmp_time = rtc_read();
    printf("The current system time: %s\r", ctime(&tmp_time));
}

void set_time(void) {
    time_t tmp_time = rtc_read();
    tmp_time += 20;
    rtc_write(tmp_time);
}

void app_start(int, char**){
    // set 115200 baud rate for stdout
    get_stdio_serial().baud(115200);
    printf("\r\n---start---\r\n");


    /* Schedule the blinking LED */
    minar::Scheduler::postCallback(blinky).period(minar::milliseconds(500));
    /* Display the current time every second */
    minar::Scheduler::postCallback(print_time).period(minar::milliseconds(1000));
    /* RTC time update, 1.5 seconds from now */
    minar::Scheduler::postCallback(set_time).delay(minar::milliseconds(1500));

}