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Time problem
Posted: Mon Feb 01, 2016 6:43 pm
by RTOSman
Hello there, i did an arduino program with the chibios library.
I create 2 theade the first thread is high priority+1
static THD_FUNCTION(Thread1, arg) {
while (1) {
while (1) {
my_function();
chThdSleepMicroseconds(10);
}
}
the Second thread high priority-1
static THD_FUNCTION(Thread2, arg) {
while (1) {
Serial.print(result);
chThdSleepMicroseconds(1);
}}
My problem is that i'm not sure that my first thread start every 10 MS
sconde problem, i want the first thread start one time every 10 MS is there other function without chThdSleepMicroseconds();
thanks
Re: Time problem
Posted: Mon Feb 01, 2016 9:20 pm
by utzig
It should be chThdSleepMilliseconds instead of chThdSleepMicroseconds! Also in your first thread, having two nested infinite loops:
doesn't seem very useful...
Fabio Utzig
Re: Time problem
Posted: Mon Feb 01, 2016 11:03 pm
by Giovanni
Also note that times are rounded up to the clock tick period, if your system tick is 100Hz then the resolution is 1/100 of second.
Giovanni
Re: Time problem
Posted: Tue Feb 02, 2016 11:06 pm
by RTOSman
Hello, thanks for your answer.
@utzig yes i did milisecond and just one while(1), i typed wrong message ^^.
@GiovanniBut how do i know the resolution of my system ??
i have arduino uno. could you tell me what's the resolution please
and could you explain me "times are rounded up to the clock tick period" i am fan of CHIBIOS i love this RTOS
Thanks
Re: Time problem
Posted: Wed Feb 03, 2016 1:46 am
by utzig
If your crystal is 16MHz and you're using the library from this repo
https://github.com/greiman/ChibiOS-Arduino, your tick will be 1/976 which is around 1ms. The minimum sleep time is than 1ms. More info on this thread:
viewtopic.php?f=21&t=2647
Re: Time problem
Posted: Thu Feb 04, 2016 8:20 pm
by RTOSman
and should i change the CH_TIME_QUANTUM value ??
Re: Time problem
Posted: Thu Feb 04, 2016 11:13 pm
by utzig
Why would you?
Re: Time problem
Posted: Fri Feb 05, 2016 12:31 am
by RTOSman
The poste that you gave me. i read that some one modify the value CH_TIME_QUANTUM.
what ever, i have a question. for exemple i have a function in my thread, i want my function doesn't exceed 10 Ms. or i want my function execute every 10MS. how do i program that ?
Thanks
Re: Time problem
Posted: Fri Feb 05, 2016 9:18 am
by Giovanni
Re: Time problem
Posted: Fri Feb 05, 2016 11:20 am
by RTOSman
Thanks for the replay, but what is the difference between this
Code: Select all
msg_t my_thread(void *param) {
systime_t time = chTimeNow(); // T0
while (true) {
time += MS2ST(1000); // Next deadline
do_something();
chThdSleepUntil(time);
}
}
and this
Code: Select all
static THD_FUNCTION(Thread1, arg) {
systime_t time = chTimeNow(); // T0
while (true) {
time += MS2ST(1000); // Next deadline
do_something();
chThdSleepUntil(time);
}
}
and i have a difficulte to understand the the system tick period ?? could you explain me what is it please