hello, i have a problem with thread.
in the beginning of my code i do : US.Resume(); (i had already did US.Start()
than at the end, US.Suspend();
but my Ultrasonic Sensor will not restart.
help plz
how can i pause US detecting and resume it after ?.
@ Tirmit -
We need more information and show us your code please
public static int usVal;
public static void usRead() //TREAD DU US SENSOR
{
bool infini = true;
while (infini==true)
{
usVal = USdetect(_pin);
}
}
public static Thread US = new Thread(usRead);
public static TristatePort _pin;
...Main()...{
_pin = new TristatePort((Cpu.Pin)FEZ_Pin.Digital.Di52, false, false, Port.ResistorMode.Disabled);
US.Start();
while(true){
while (ScanAvant > 15 || ScanAvant < 10)
{
Thread.Sleep(100);
Debug.Print(ScanAvant.ToString());
ScanAvant = usVal;
}
......
US.suspend();
.....
//it is a long code
US.resume();
}}
i use parallax ping sensor :http://www.parallax.com/tabid/768/productid/92/default.aspx
and i use Thread because the sensor doesnât work when i use Servo.
But it doesnât work
@ Tirmit Have you seen this driver on codeshare for the PING))) sensor?
yes, i used this code to create :
public static int USdetect(TristatePort _pin)
{
const int TicksPerMicrosecond = (int)TimeSpan.TicksPerMillisecond / 1000;
_pin.Active = true;
_pin.Write(true);
Thread.Sleep(5);
_pin.Write(false);
_pin.Active = false;
bool high = false;
do
{
high = _pin.Read();
}
while (!high);
long startTime = System.DateTime.Now.Ticks;
while (high)
{
high = _pin.Read();
}
int ticks = (int)(System.DateTime.Now.Ticks - startTime);
int microSeconds = (ticks / TicksPerMicrosecond);
return (microSeconds / 29 / 2);
}
If you want to control the thread more accurately I would use an auto reset or manual reset event instead of relying on suspend/resume. You can easily âmissâ a pulse with suspend/resume and the reading thread will be in a deadlock or something like that.
yes, i want to control my thread, but when i do resume. The us sensor wouldnât work
is it a problem with servo ?
because, when i do US.startâŚUS.suspendâŚUS.resume and i donât use servo, it work
but if i use servoâŚit doesnât work
There is no guarantee at what instruction the thread will be suspended. For example it can be suspended at the following line:
while (!high);
So while thread is suspended the sensor itself will send the high pulse back.
So when you resume the thread the pin is already low and the code will be stuck in the infinite loop until you restart the board.
As I said before use AutoResetEvent or ManualResetEvent to control the thread.
ok, i ma going to test that
the sensor works again ! ButâŚ
i have a question : i need to place Thread.Abort Method after each US.Suspend or US.Resume ?
example :
if i donât place US.Abort(), the sensor doesnât work in this code =>
for (int i = 85; i >= 0; i = i-5)
{
US.Abort();
ServoMove(i, servoBase);
reset.Set();
Thread.Sleep(100);
US.Resume();
Thread.Sleep(100);
int ScanDroite_lent1 = usVal;
US.Suspend();
Thread.Sleep(100);
ServoMove((i-5), servoBase);
reset.Set();
Thread.Sleep(100);
US.Resume();
Thread.Sleep(100);
int ScanDroite_lent2 = usVal;
US.Suspend();
reset.Set();
Thread.Sleep(100);
...
}
}
}
but, here :
i donât place US.Abort(), and the sensor works
ServoMove(0, servoBase);
reset.Set();
Thread.Sleep(10);
US.Resume();
Thread.Sleep(100);
ScanDoite = usVal;
...
i found the solution, thx for the help.
it works just if i write :
US.Suspend();
ServoMove(90-i, servoBase); //MOVE THE SERVO
reset.Set(); //AUTORESETEVENT
US.Resume();
Thread.Sleep(100);
ScanDroite_lent2 = usVal; // receive us values