5 replies to this topic

[rubenhak]

Hi Everybody,

 

I'm having troubles with making the sonar sensors work. I used both Parallax Ping and HC-SR04, but neither of those worked well.

 

The problem with HC-SR04 is that I'm always getting -1 as result. The code is from this library: http://forums.netdui...ic-rangefinder/

Tried connecting to different digital pins but it didnt work either. Powering from 5V pin of the netduino. Is there anything I'm missing?

 

The Parallax Ping works "sometimes".  If it works i get correct distance result. The trouble with this one is that sometimes it gets stuck in following loop:

while (lineState)lineState = _port.Read();

Using this code:

http://forums.netdui...rasonic-sensor/

 

Are those sensors sensitive to the power source? Running from USB. 

 

Any help is highly appreciated.

 

Thansk,

Ruben

 

P.S. I use Netduino Plus 2 with latest firmware 4.2.2.

 

 

 

 

[baxter]

I modified the code from here,

http://forums.netdui...asures-jumping/

 

and the files are here for Netduino Plus 2 (in VB),

https://www.dropbox....0a7Geue?v=0mwng

 

The cheap HC-SR04 modules are spotty at best. I wasted a lot of time with a bad one. The above code works just fine. I merely added some smoothing routines. The module is powered from the Netduino 5V pin.

 

[rubenhak]

I modified the code from here,

http://forums.netdui...asures-jumping/

 

and the files are here for Netduino Plus 2 (in VB),

https://www.dropbox....0a7Geue?v=0mwng

 

The cheap HC-SR04 modules are spotty at best. I wasted a lot of time with a bad one. The above code works just fine. I merely added some smoothing routines. The module is powered from the Netduino 5V pin.

 

Thank you, I will try to use and see how it works.

Are there any limitations on the pins which I can use?

[rubenhak]

Still didn't work. If I use PIN4 it gets stuck in while (lineState == false). If I connect it to PIN5 it gets stuck in while(lineState).

 

Also when I connect it to PIN13 every time the port Writes(true) or false, it turnes on or off netduinos blue LED. 

 

What am i doing wrong?

 

Thanks,

Ruben

        private int GetDistance()        {            // First we need to pulse the port from high to low.            _port.Active = true; // Put port in write mode            _port.Write(true);   // Pulse pin            _port.Write(false);            _port.Active = false;// Put port in read mode;                bool lineState = false;            // Wait for the line to go high, for start of pulse.            while (lineState == false)                lineState = _port.Read();            long startOfPulseAt = System.DateTime.Now.Ticks;      // Save start ticks.            // Wait for line to go low.            while (lineState)                lineState = _port.Read();            long endOfPulse = System.DateTime.Now.Ticks;          // Save end ticks.             int ticks = (int)(endOfPulse - startOfPulseAt);            return ticks / 580;        }

adsf

[Shadi]

The only way you're going to get somewhat accurate measurements is to use an Interrupt and calculate based off the time parameter.

public UltraSoundSensor(Cpu.Pin trigger, Cpu.Pin echo){	this.pinTrigger = new OutputPort(trigger, false);	this.pinEcho = new InterruptPort(echo, false, Port.ResistorMode.Disabled, Port.InterruptMode.InterruptEdgeBoth);	pinEcho.OnInterrupt += new NativeEventHandler(pinEcho_OnInterrupt);				isBusy = false;	LastEchoDelayTicks = 0;	LastEchoDelayMilliSeconds = 0;}

protected void pinEcho_OnInterrupt(uint data1, uint data2, DateTime time){	if (data2 == 0)	{		ticksEndEcho = time.Ticks;		LastEchoDelayTicks = ticksEndEcho - ticksStartEcho;		LastEchoDelayMilliSeconds = LastEchoDelayTicks / TimeSpan.TicksPerMillisecond;		LastEchoDelayMeters = LastEchoDelayMilliSeconds * 0.3432;		isBusy = false;		if (Pong != null)			Pong(LastEchoDelayMeters);	}	else	{		ticksStartEcho = time.Ticks;	}}

This won't be as accurate as baxter's temperature/smoothed version.

[rubenhak]

Shadi, The trouble is that I'm not getting any interrupt on a echo port.