Page 1 of 2
Question to Giovanni
Posted: Tue Feb 16, 2016 7:55 pm
by RTOSman
Hello Mr Giovanni. i use chibios librrary for arduino and i find it powerful i tried many application on arduino uno board. but arduino board has not a real time clock. the timer of arduino it's not really accurate, so i want to use RTC DS3231. my question is how to make the function chThdSleepMilliseconds or ThreadSleepMicroseconds work with RTC DS3231
Please answer
Re: Question to Giovanni
Posted: Tue Feb 16, 2016 8:22 pm
by Giovanni
The OS does not need necessarily an RTC, it just need a periodic interrupt, any periodic interrupt source can be used.
Giovanni
Re: Question to Giovanni
Posted: Tue Feb 16, 2016 8:34 pm
by RTOSman
The problem is the chVTGetSystemTimeX() not accurate on the arduini uno. i did this code
Code: Select all
while (1)
{
start += 10;
Serial.println(chVTGetSystemTimeX()/1000);
}
i compare the values of chVTGetSystemTimeX()/1000) with my stopwatch of my phone. after 3 minutes the values of chVTGetSystemTimeX()/1000) not same with the values of my stop watch. 400 seconds from chVTGetSystemTimeX() and 399 from the stopwatch. and overt the time i had 500 497.
i did som modificaion to get 1000 ticks = 1000 ms in board.c
Code: Select all
#include "ch.h"
#include "hal.h"
CH_IRQ_HANDLER(TIMER0_COMPA_vect) {
CH_IRQ_PROLOGUE();
OCR0A += 250; // ****** ADD THIS LINE FOR 1.000 MS TICK************
chSysLockFromISR();
chSysTimerHandlerI();
chSysUnlockFromISR();
CH_IRQ_EPILOGUE();
}
/*
* Board-specific initialization code.
*/
void boardInit(void) {
/*
* Timer 0 setup.
*/
OCR0A = 128;
TIMSK0 |= (1 << OCIE0A); /* IRQ on compare. */
TCCR0A &= ~((1 << WGM00) | (1 << WGM01)); // ****** ADD THIS LINE FOR 1.000 MS TICK************
}
and i change this
#define CH_CFG_ST_FREQUENCY 1000 // WHG.
so please MR Giovanni, how do i to get exactly the real time please. i use arduino uno.
find me a solution
Re: Question to Giovanni
Posted: Tue Feb 16, 2016 8:37 pm
by Giovanni
Just set CH_CFG_ST_FREQUENCY to the exact timer frequency and you will have the best approximation. Alternatively provide a system tick from some external timer to an interrupt pin.
Giovanni
Re: Question to Giovanni
Posted: Tue Feb 16, 2016 8:53 pm
by RTOSman
how do i know the exact timer frequency value of CH_CFG_ST_FREQUENCY.
i have arduino uno
please
Re: Question to Giovanni
Posted: Tue Feb 16, 2016 9:28 pm
by RTOSman
Giovanni you didn't answer me !!!
Re: Question to Giovanni
Posted: Tue Feb 16, 2016 9:55 pm
by Giovanni
You should not expect answers in real time...
I don't have Arduino one and cannot provide specific support, what I can do is to give generic advice. Studying documentation about your platform is up to you.
Giovanni
Re: Question to Giovanni
Posted: Tue Feb 16, 2016 10:14 pm
by RTOSman
but you did a library for arduino !!!!
Re: Question to Giovanni
Posted: Tue Feb 16, 2016 10:26 pm
by Giovanni
Re: Question to Giovanni
Posted: Tue Feb 16, 2016 11:09 pm
by RTOSman
Yes this library