I have a program with 2 timer functions like this (p_maj_input and p_maj_output_motion are equal so the period of both timer is the same):
maj_input = timer('ExecutionMode','fixedRate','Period',p_maj_input,'TasksToExecute', ...
floor(Tmeasurement/p_maj_input)-1,'TimerFcn',{#time_append,p_maj_input,HR_all,freq_HR, ...
BVP_all,freq_BVP,TEMP_all,freq_TEMP,ACC_x_all,ACC_y_all,ACC_z_all,freq_ACC,EDA_all,freq_EDA, ...
folder_all,all_dir,num_dir}); start(maj_input);
maj_output_motion=timer('ExecutionMode','fixedRate','Period',p_maj_output_motion,'TasksToExecute', ...
floor(Tmeasurement/p_maj_output_motion)-1,'TimerFcn',{#output_motion_append, ...
freq_MOTION,freq_mvt_score,freq_walk,p_maj_output_motion,p_maj_output_walk,folder_all,all_dir,num_dir});%,'StartDelay',min(5,p_maj_output_motion)); %startDelay must be min 5 for walk detection start(maj_output_motion);
In each timer callback function there is a loop over subfolders contained in a folder that is selected at the beginning of the program.
output_motion_append(obj,event,freq_MOTION,freq_mvt_score,freq_walk,p_maj_output_motion,p_maj_output_walk,folder_all,all_dir,num_dir)
fprintf('motion %d\n',obj.TasksExecuted)
toc
for folder_index=1:num_dir
[folder_original,folder_fictive] = subfolderFunction(all_dir, folder_all, folder_index);
fileName=strcat(folder_fictive,'\ACC.csv');
[ACC_time, ACC_x, ACC_y, ACC_z] = loadValuesE4_acc(fileName);
% Motion Amount
[agitation,agitation_ts] = identifyAgitation(ACC_x,ACC_y,ACC_z,ACC_time);
agitation=agitation';
len1=length(agitation);
if len1<=freq_MOTION*p_maj_output_motion
i_init1=1;
elseif len1>freq_MOTION*p_maj_output_motion
i_init1=len1-freq_MOTION*p_maj_output_motion+1;
end
writematrix([agitation(i_init1:len1)],strcat(folder_fictive,'\MOTION_output.csv'),'WriteMode','Append');
writematrix([mvt_score(i_init2:len2)],strcat(folder_fictive,'\neurologicScore_output.csv'),'WriteMode','Append');
end
end
Everything works fine if the number of subfolders is lower than 4 : the good values appear in the files on which is carried out the writematrix function. And the timer callback function are are called one after the other, so both timer work simultaneously.
However if there are 5 subfolders or more, it is not the good values and using the debugging I noticed that the first callback function is triggered the number of 'TasksToExecute', and then only the second callback function seems to be called. That is to say the 2 timers don't work simultaneously.
I have tried to increase p_maj_input and p_maj_output_motion to see if the problem is that matlab can't finish to run before another timer callback function is called but still for 5 subfolders I get the same problem.
Does anyone know where my problem is coming from?
This behavior occurs because one timer hasn't finished executing by the time it triggers again, so the second timer never has a chance to execute until the first timer is finished. If you change the ExecutionMode from 'fixedRate' to 'fixedSpacing', then you'll guarantee that there's time for the second timer to execute.
function duelingTimers()
disp('With ExecutionMode = fixedRate')
t1 = timer('ExecutionMode','fixedRate','Period',0.1,'TasksToExecute',5,'TimerFcn',#timerFcn1);
t2 = timer('ExecutionMode','fixedRate','Period',0.1,'TasksToExecute',5,'TimerFcn',#timerFcn2);
cleanup = onCleanup(#()delete([t1,t2]));
function timerFcn1(~,~)
pause(0.2)
disp('Timer 1');
end
function timerFcn2(~,~)
pause(0.2)
disp('Timer 2');
end
start(t1),start(t2)
wait(t1)
wait(t2)
disp(newline)
disp('With ExecutionMode = fixedSpacing')
t1.ExecutionMode = 'fixedSpacing';
t2.ExecutionMode = 'fixedSpacing';
start(t1),start(t2)
wait(t1)
wait(t2)
end
I'm working on a timer that needs to do some calculations and run some functions at a certain interval. I'm trying to keep the interval as big as possible, but I need it to be kind of fine grained.
Here is the periodic timer with some of the stuff that needs to happen.
So as you can see, every second (the milliseconds passed % 1000 == 0) it will do some stuff if some conditions are met. But also every 10 milliseconds I need to check some stuff.
It seems this is a bit too much, and after running the timer for 2 minutes it already drags 1 second behind. I guess I'm approaching this the wrong way. Could/should I somehow put all that logic in a function that just runs async so the timer can just keep going.
It's not the end of the world if the timer display drags for a few milliseconds every now and then, if it catches up later. But now the whole timer just drags.
_timer = Timer.periodic(Duration(milliseconds: 10), (timer) {
passedMilliseconds = passedMilliseconds + 10;
// METRONOME BEEP AND BLINK
if (passedMilliseconds % currentTimerSettingsObject.milliSecondDivider == 0) {
_playMetronomeBeep();
_startMetronomeBlink();
}
// ONE SECOND
if (passedMilliseconds % 1000 == 0) {
secondsDuration--;
// COUNTDOWN
if (secondsDuration < currentTimerSettingsObject.countDown + 1) {
_player.play('sounds/beep.mp3');
}
// SET COUNTDOWN START VALUES
if (secondsDuration == currentTimerSettingsObject.countDown) {
isCountdown = true;
}
notifyListeners();
}
// TIME IS UP
if (secondsDuration < 0) {
switchToNextTimer();
notifyListeners();
}
});
}
You cannot rely on a timer to deliver events exactly on time. You need to use a more exact method than simply incrementing a counter by 10 on every tick. One example would be to start a Stopwatch before the timer and then (knowing that your ticks will only be on approximately 10ms intervals) read stopwatch.elapsedMilliseconds and base your decisions on that.
You will need to change your logic a bit. For example, you want to know when you pass a 1 second boundary. Previously, with your exact increments of 10 you knew you would eventually reach a round 1000. Now, you might see 995 followed by 1006, and need to deduce that you've crossed a second boundary to run your per second logic.
I'm trying to program Zolertia z1 node in Contiki, i need counter to go from 0 to 120, etimer should be set to 1 second delay(etimer_set(&et, CLOCK_SECOND)), and when i try to do counting it's constantly printing out same number (0 or 1), i think i should use PROCESS_WAIT_EVENT_UNTIL(etimer_expired(&et)) and probably etimer_restart,and after each second counter should be incremented and printed out (1, 2 ,3 ...), but obviously I'm not doing something correct in while loop or functions are not good?
This code works for me:
PROCESS_THREAD(hello_world_process, ev, data)
{
static struct etimer et;
static int counter;
PROCESS_BEGIN();
etimer_set(&et, CLOCK_SECOND);
while(1) {
PROCESS_WAIT_EVENT_UNTIL(etimer_expired(&et));
printf("timer called, counter=%u\n", counter++);
etimer_reset(&et);
}
PROCESS_END();
}
Potential pitfalls:
there is no process-local storage for in-process variables in Contiki
processes. Meaning - if you want to save the values of local
variables across yields (such as PROCESS_WAIT_EVENT_UNTIL), declare
them as static. Most likely this is the problem you're facing, as it woul lead to the counter value being reset.
etimer_restart will drift, use etimer_reset instead to get the duration of exactly 120 seconds.
How do you view and amend the start time of a timer object in Matlab? The closest I can get is the "StartDelay" element of the timer object :
all_timers = get(timerfind);
where each element of the returned structure array is one timer object. The various elements of the structure are (for example):
AveragePeriod: NaN
BusyMode: 'drop'
ErrorFcn: ''
ExecutionMode: 'singleShot'
InstantPeriod: NaN
Name: 'timer-1'
ObjectVisibility: 'on'
Period: 1
Running: 'on'
StartDelay: 7.200175000000000e+003
StartFcn: ''
StopFcn: ''
Tag: ''
TasksExecuted: 0
TasksToExecute: Inf
TimerFcn: #myFcn
Type: 'timer'
UserData: []
According to:
http://www.mathworks.co.uk/help/matlab/ref/timer-class.html
"StartDelay" is: Number greater than or equal to 0 that specifies the delay, in seconds, between the start of the timer and the first execution of the function specified in TimerFcn.
but unless I know when the timer object was started/created/initiated, the StartDelay is no real help?
The startFun can be used to evaluate a function on timer start, which could store the start time in the userData of the timer
Most simple
Define a function such as;
function myStartFcn(hTimer,~)
hTimer.UserData = now;
end
and set this to be the startFcn of the timer
hTimer = timer();
hTimer.StartFcn = #myStartFcn
A better? example
userData is a useful field we may want to use it for many things, in which case making it a structure and setting this as a field would be better. also now gives datenum format which may not be ideal, clock is another possibility;
function myStartFcn(hTimer,~)
tempStruct = hTimer.UserData;
tempStruct.startTime = clock;
hTimer.UserData = tempStruct;
end
Also it may be worth clearing this when the timer is stopped and storing the last run time in seconds
function myStopFcn(hTimer,~)
tempStruct = hTimer.UserData;
tempStruct.lastRunTime = etime(clock,tempStruct.startTime)
tempStruct.startTime = []
hTimer.UserData = tempStruct;
end
I need to debounce an input-stream.
At the first occurrence of state 1 I need to wait for 5 Seconds and verify if the laste state was also 1.
Only than I have a stable signal.
(time) 0-1-2-3-4-5-6-7-8-9
(state) 0-0-0-0-0-1-0-1-0-1
(result) -> 1
Here is an example of a non-stable signal.
(time) 0-1-2-3-4-5-6-7-8-9
(state) 0-0-0-0-0-1-0-1-0-0
(result) -> 0
I tried using a buffer, but a buffer has fixed starting point and I need to wait for 5 seconds starting with my first event.
Taking your requirements literally
At the first occurrence of state 1 I need to wait for 5 Seconds and
verify if the laste state was also 1. Only than I have a stable
signal.
I can come up with a few ways to solve this problem.
To clarify my assumptions, you just want to push the last value produced 5 seconds after the first occurrence of a 1. This will result in a single value sequence producing either a 0 or a 1 (ie. regardless of any further values produced past 5 seconds from the source sequence)
Here I recreate you sequence with some jiggery-pokery.
var source = Observable.Timer(TimeSpan.Zero,TimeSpan.FromSeconds(1))
.Take(10)
.Select(i=>{if(i==5 || i==7 || i==9){return 1;}else{return 0;}}); //Should produce 1;
//.Select(i=>{if(i==5 || i==7 ){return 1;}else{return 0;}}); //Should produce 0;
All of the options below look to share the sequence. To share a sequence safely in Rx we Publish() and connect it. I use automatic connecting via the RefCount() operator.
var sharedSource = source.Publish().RefCount();
1) In this solution we take the first value of 1, and then buffer the selected the values of the sequence in to buffer sizes of 5 seconds. We only take the first of these buffers. Once we get this buffer, we get the last value and push that. If the buffer is empty, I assume we push a one as the last value was the '1' that started the buffer from running.
sharedSource.Where(state=>state==1)
.Take(1)
.SelectMany(_=>sharedSource.Buffer(TimeSpan.FromSeconds(5)).Take(1))
.Select(buffer=>
{
if(buffer.Any())
{
return buffer.Last();
}
else{
return 1;
}
})
.Dump();
2) In this solution I take the approach to only start listening once we get a valid value (1) and then take all values until a timer triggers the termination. From here we take the last value produced.
var fromFirstValid = sharedSource.SkipWhile(state=>state==0);
fromFirstValid
.TakeUntil(
fromFirstValid.Take(1)
.SelectMany(_=>Observable.Timer(TimeSpan.FromSeconds(5))))
.TakeLast(1)
.Dump();
3) In this solution I use the window operator to create a single window that opens when the first value of '1' happens and then closes when 5 seconds elapses. Again we just take the last value
sharedSource.Window(
sharedSource.Where(state=>state==1),
_=>Observable.Timer(TimeSpan.FromSeconds(5)))
.SelectMany(window=>window.TakeLast(1))
.Take(1)
.Dump();
So lots of different ways to skin-a-cat.
It sounds (at a glance) like you want Throttle, not Buffer, although some more information on your use cases would help pin that down - at any rate, here's how you might Throttle your stream:
void Main()
{
var subject = new Subject<int>();
var source = subject.Publish().RefCount();
var query = source
// Start counting on a 1, wait 5 seconds, and take the last value
.Throttle(x => Observable.Timer(TimeSpan.FromSeconds(5)));
using(query.Subscribe(Console.WriteLine))
{
// This sequence should produce a one
subject.OnNext(1);
subject.OnNext(0);
subject.OnNext(1);
subject.OnNext(0);
subject.OnNext(1);
subject.OnNext(1);
Console.ReadLine();
// This sequence should produce a zero
subject.OnNext(0);
subject.OnNext(0);
subject.OnNext(0);
subject.OnNext(0);
subject.OnNext(1);
subject.OnNext(0);
Console.ReadLine();
}
}