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Analog in put C# coding

Started by swestcott, Jan 09 2011 12:30 AM

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14 replies to this topic

#1 swestcott

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Posted 09 January 2011 - 12:30 AM

I have a range finder that outputs 6.4mV per inch I want to read that input and lets say if less than or = to 10 inches do X if grater than 10 inches do Y is this even possible?

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#2 phantomtypist

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Posted 09 January 2011 - 03:59 AM

I have a range finder that outputs 6.4mV per inch I want to read that input and lets say if less than or = to 10 inches do X if grater than 10 inches do Y

is this even possible?

Sounds like a simple if/else statement. We might be able to help you better if you explain further (i.e. sensor model, brand, etc.) that way someone can reference the datasheet.

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#3 swestcott

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Posted 09 January 2011 - 02:27 PM

Sounds like a simple if/else statement. We might be able to help you better if you explain further (i.e. sensor model, brand, etc.) that way someone can reference the datasheet.

OK thanks it is the Maxbotix LV-EZ1 http://www.sparkfun.com/products/639
here is the data sheet http://www.maxbotix....1-Datasheet.pdf

I was thinking that I could connect it to the 3.3V and the Aref and one of the analog inputs on the netduino the data sheet says at 3.3v the out put is around 6.4mV per inch. I was hoping to have this interrupt the forward motion of a robot cause one set of wheels spin the other way turning to avoid objects in front of it then return to moving forward. I am trying to understand how to read the analog input voltage in C# the data sheet says it sends an analog reading constantly so no timing is needed? and after rereading I saw this "Analog, (Vcc/512) / inch" I have powered it up by it self and attached a meter to the output and did see around 6.4mV per inch output but when something is closer than 6 inches the output stops showing changes this is why I chose 10 inches as the distance for making the turn.

I have all the motor control code figured out and have the bot moving forward or turning in a circle
here is a photo of the finished bot.

thanks for your help

P1012974.JPG 1.1MB 49 downloads

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#4 bill.french

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Posted 09 January 2011 - 02:40 PM

That's a cool little car. Is this all you're looking for, to test? Hook up 3.3v to aref, and the analog output from the sensor to A5 (plus whatever else the sensor needs, like power and ground), and i think you'll be all set to test.

using System.Text;
using Microsoft.SPOT;
using System.Threading;
using SecretLabs.NETMF.Hardware;
using SecretLabs.NETMF.Hardware.Netduino;


namespace NDP_SocketSender1
{
    public class Program
    {
        public static void Main()
        {
       
            AnalogInput a5 = new AnalogInput(Pins.GPIO_PIN_A5);

            while (true)
            {
                string s = a5.Read().ToString();
                Debug.Print(s);
                Thread.Sleep(100);
            }
        }
    }
}

The above code is from here.

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#5 swestcott

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Posted 09 January 2011 - 04:11 PM

Can I use the 3.3v connected to Aref as the power source for the sensor I saw in another thread that was what you do? and where should I be looking for this out put I thought it would show in a windows in studio express? sorry kinda new to C# coming from a VB background and self taught on that I understand your code sample but not sure on reading output Thia is what I have Analog out on sensor connected to A5, GND to GND, Aref to 3.3 to power in on sensor run the code no errors but not sure what I am looking for? Thanks

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#6 Jan Olof

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Posted 09 January 2011 - 04:19 PM

Hi He uses Debug.Print that output should you see in the Output window when running the debugger. On my screen this window pops up in the lowe left corner, think I have standard configuration but not sure. And yes you can take some power from the 3.3V pin, but I am not sure how much is left after the Netduino have taken it´s share from the regulator. /Jan Olof

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#7 bill.french

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Posted 09 January 2011 - 05:01 PM

I am not sure how much is left after the Netduino have taken it´s share from the regulator.

/Jan Olof

Should be plenty! And yes, debug.print should put stuff in the "output" window -- it should be in the lower left, although you might have to select the "output" tab. I can't remember, I set it up my visual studio layout some time ago, and the settings stick.

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#8 swestcott

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Posted 09 January 2011 - 06:07 PM

OK cool yep just chose output window from the Debug menu the out put is a bit unstable but I can work with it I think but this an integer and not a string so the code I was thinking will not work if (s >= 20); I do get an output though a big step forward

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#9 bill.french

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Posted 09 January 2011 - 06:32 PM

the line with the a5.read, I convert to a string, I believe it normally returns a number, so if you did something like:

int i = a5.read();
if (i > 20)
{
// do whatever
}

If you want to get the analog readings in mV, search the forums for "setrange".

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#10 swestcott

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Posted 09 January 2011 - 07:15 PM

the line with the a5.read, I convert to a string, I believe it normally returns a number, so if you did something like:
int i = a5.read();
if (i > 20)
{
// do whatever
}
If you want to get the analog readings in mV, search the forums for "setrange".

Awesome! thanks I will post a video of it avoiding stuff tonight

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#11 FDC30

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Posted 01 May 2012 - 02:32 AM

Heey guys.. Question, my ultrasonic range finder sensor(Maxbotix LV-EZ1)currently works fine with a 5 V supply (hard wired to USB), however, in a 3.3V Lipo battery powered case, the ultrasonic conversion leads to significant errors. Currently I accept Analog input from the ultrasonic to the ardupilot. Is there a correct conversion arduino code for the ultrasonic (Maxbotix LV-EZ1) sensor when powered by a 3.3 V Lipo battery? Any ideas why am I getting this when I do use the 3.3v Lipo Battery?

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#12 Mario Vernari

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Posted 01 May 2012 - 07:56 AM

Heey guys.. Question, my ultrasonic range finder sensor(Maxbotix LV-EZ1)currently works fine with a 5 V supply (hard wired to USB), however, in a 3.3V Lipo battery powered case, the ultrasonic conversion leads to significant errors. Currently I accept Analog input from the ultrasonic to the ardupilot. Is there a correct conversion arduino code for the ultrasonic (Maxbotix LV-EZ1) sensor when powered by a 3.3 V Lipo battery? Any ideas why am I getting this when I do use the 3.3v Lipo Battery?

The sensor seems working fine even below 3V (from the specs).
Not sure about your problem in general, though. Are you using Arduino or Netduino?

Biggest fault of Netduino? It runs by electricity.

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#13 FDC30

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Posted 01 May 2012 - 12:50 PM

Heey Mr. Vernari thanks for your response. Yes, I am using Arduino(Ardupilot)system. EZ1-Ardupilot-3.3V battery. It works really fine with the USB port connection 5V and yes I have 4 different 3.3v batteries brand new but for any unknown reason, when I connect the 3.3v on it, the ultrasonic conversion leads to significant errors. Noise. Any Ideas, I know it is weird.

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#14 Giuliano

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Posted 18 September 2012 - 05:31 AM

Does the EZ1 works in low light condition or it doesn't matter because it works just with a ultrasonic wave to determine distance to objects? Does humidity or heat affects the reading?

Solo s� que no s� nada

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#15 Geancarlo2

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Posted 18 September 2012 - 11:57 AM

Heey Mr. Vernari thanks for your response. Yes, I am using Arduino(Ardupilot)system. EZ1-Ardupilot-3.3V battery. It works really fine with the USB port connection 5V and yes I have 4 different 3.3v batteries brand new but for any unknown reason, when I connect the 3.3v on it, the ultrasonic conversion leads to significant errors. Noise. Any Ideas, I know it is weird.

Follow the datasheet's instructions to calibrate the sensor and adjust your code to take this into account:

AN – Outputs analog voltage with a scaling factor of (Vcc/512) per
inch. A supply of 5V yields ~9.8mV/in. and 3.3V yields ~6.4mV/in.
The output is buffered and corresponds to the most recent range data.

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