Using millis() like in Arduino.

RE: Using millis() like in Arduino.

schef — Thu, 12 Oct 2017 06:51:41 GMT

Aha..i had problems yesterday thank God i connect the buzzer to beep on every startup and it was beeping every 8 minutes :)

The use-case was:

#define MINUTE 60*1000

uint32 millisPassed(uint32_t localMillis)
{
    return(compareMillis(localMillis, millis()));
}

This is what i used for help and the requirement was:

if(millisPassed(lastMessage) > 15 * MINUTE)
{
    sd_nvic_SystemReset();
}

Is there another solution for the OVERFLOW without using hardcoded number but the PRESCALER?

RE: Using millis() like in Arduino.

Nicolas Brunner — Wed, 11 Oct 2017 14:19:01 GMT

I made an error, the overflow should be #define OVERFLOW ((uint32_t)(0xFFFFFF/32.768)) because the app_timer_cnt_get() use the RTC who is a 24 bits counter.

RE: Using millis() like in Arduino.

Nicolas Brunner — Wed, 11 Oct 2017 14:12:13 GMT

You won't be able to measure millisecond with a prescaler of 32768

RE: Using millis() like in Arduino.

schef — Wed, 11 Oct 2017 13:48:51 GMT

I had some more ploblems with #define OVERFLOW ((uint32_t)(0xFFFFFFFF/32.768)). It should have been something like #define OVERFLOW ((uint32_t)((512*32768)/32.768)) because of PRESCALER which is 32768.

RE: Using millis() like in Arduino.

schef — Tue, 03 Oct 2017 11:32:33 GMT

You are right. I will edit the post.

RE: Using millis() like in Arduino.

Nicolas Brunner — Mon, 02 Oct 2017 13:35:03 GMT

millisPassed() is bugged because millis() doesn't overflow after 0xFFFFFFFF but after 0xFFFFFFFF/32.768. Here is my proposition (not tested):

#define OVERFLOW ((uint32_t)(0xFFFFFFFF/32.768))

uint32_t millisPassed(uint32_t localMillis) {
  uint32_t currentMillis = millis();
  if (currentMillis < localMillis) {
    return currentMillis + OVERFLOW + 1 - localMillis;
  } else {
    return currentMillis - localMillis;
  }
}

RE: Using millis() like in Arduino.

Julie H — Fri, 29 Sep 2017 18:41:37 GMT

Not actually using milliseconds, but run a 1024Hz time-base. The time error isn't all that bad, there's no weirdness caused by imprecision and you're not using floating point on a part that may not include an FPU.

RE: Using millis() like in Arduino.

schef — Thu, 28 Sep 2017 07:03:44 GMT

What would be you solution to this idea then?

RE: Using millis() like in Arduino.

Julie H — Wed, 27 Sep 2017 16:03:21 GMT

Please keep in mind that 1,000 does not go evenly into 32,768. The above solution can misbehave if the application expects each of the values modulo 1000 to be returned once, and only once, every wall-clock 1 millisecond.

RE: Using millis() like in Arduino.

Mahesh Venkitachalam — Tue, 19 Sep 2017 02:39:44 GMT

Nice! Might be good to also show how the timer is started and stopped. Also app_timer_cnt_diff_compute can compute the diff taking overflow into account.