I have a 2gb microSD card that I pulled from my Blackberry and I plugged it into my Netduino Plus, and I noticed that it is very slow to read files. It is even slow when using a USB-to-microSD card reader. I am comparing to the speed of a standard USB drive. Are USB read times normally faster than microSD, or am I doing something wrong? Is there a way to read USB drives with a Netduino, i.e. with a compatible USB shield or something? I need faster read times somehow. Even a 20kb file takes too long.

Could be a problem with the SD card... I'm re-formatting it now. I don't have a second one around to try. Perhaps the issue is more related to my code and what I am doing. I am reading a file off of the SD card via a Filestream, and then I am sending the data out onto the Netduino's UART to another device. I am sending it at 1024 bytes at a time, but I wonder if I am running into speed issues because of the fact that I'm re-assembling it for transport onto the UART. The other device also then has to process it. I'm not sure where the bottleneck is. I'd like to think it isn't my code, but that's also possible.

However the transistors are connected to the 5v onboard power, so I expected the output to be at 5V rather than 3.3v is that correct?

I have confirmed the NetDuino is outputting 5v on the 5v onboard output and if I connect the relay directly it works fine.

Any ideas, have I misunderstood something?

Thanks,

Charlie M

I don't quite follow this. Are you connecting the transistors to the 3v3 or the 5v on the Netduino? The Netduino has outputs of 3.3vdc and 5vdc depending on which pin you use.

Also, what is the application with the kettles? When you say kettles, do you mean like teakettles for boiling water?

However the transistors are connected to the 5v onboard power, so I expected the output to be at 5V rather than 3.3v is that correct?

I have confirmed the NetDuino is outputting 5v on the 5v onboard output and if I connect the relay directly it works fine.

Any ideas, have I misunderstood something?

Thanks,

Charlie M

I don't quite follow this. Are you connecting the transistors to the 3v3 or the 5v on the Netduino? The Netduino has outputs of 3.3vdc and 5vdc depending on which pin you use.

Also, what is the application with the kettles? When you say kettles, do you mean like teakettles for boiling water?

---> Edit, I think I follow now. Do you mean you are getting 3.3vdc from the I/O pins? That is what you will get. The I/O pins output 3.3v but are 5v tolerant. See the lower right corner of the spec sheet.


You will need to use the 5v supply pin to power your 5v device.

Oops, I didn't mean to double post! Sorry!

P.S., when it says that the I/O pins are 5v tolerant, it means you can connect a 5v signal input to the pins without damaging them.

Is it possible to boot an install of Linux with the on-board microSD card? Can I "auto-boot" Linux when the SD card powers up? I want to be able to run Linux on the microSD card so that the Netduino would basically become an MCU running Linux and I could then communicate to the Linux install from C#. Is this possible?

Hi,

Can someone please assist me with wiring this circuit? Thanks!

It's got going to work, it's missing the cold fusion reactor and the warp field coils!
Hmn I see it's missing the flux regulator and the sid chip!

I was having trouble finding scarab beetles, and my electric eel won't stay still, but this information throws another wrench into the works. Or maybe I just need to throw a real wrench and another solder blob in there somewhere as replacement for the other items? Hmmm... any other suggestions?

Euh... LOL!

"Not a resistor; wire just does this"

LOL

I've controlled 12VDC CPU fans using an NPN transistor and a PWM port on the Netduino. It works fine. Edit: I am trying to find a nice diagram for you. I will upload it here once I do.

File did not attach. See below reply.

See the attached file. I use this for reference all the time. While it is an Arduino, the same wiring for the motor (or in your case the CPU brushless motor), battery/power supply, and FET applies for the Netduino. For the FET in the diagram, I use a TIP120 Darlington transistor. I usually add a ~1K resistor in line with the PWM port as well. I've controlled small 12VDC motors and CPU fans with this wiring scheme.

Thank you for the diagram, do you by any chance have a schematic?

No sorry, that drawing is all I have.

I've been advised that I can create a "super-interrupt" pin on the Netduino by hacking the firmware. Please see quote from Chris Walker below:

...make that pin an FIQ-accelerated pin...and then use an FIQ handler in your code to count the number of pulses. Then you can easily create a "startcount" and "StopAndGetCount" managed code method to capture the values. FIQs will activate in less than one microsecond, will supercede the .NET MF runtime and...as long as they're quick...will not interfere with your code. We're using them for software PWM in an future update of the firmware, for instance.

Chris et. al,

How do I start with getting this set up? I downloaded the .Net MF Porting Kit and the Netduino Plus firmware, and I've copied the Netduino firmware into the Porting Kit directory. Now I need to know how to modify the firmware to get this operational.

Hi all, I am using some small LEDs for a project, and the goal is to create a small light fixture. I am trying to find a good material to use to diffuse the light from the LEDs. I have looked at theatrical gel filters, but these are flimsy and impermanent. Is there a way to use a piece of Lexan and coat it with diffusion material? If so, what diffusion material would work best? Or is there some kind of plastic like Lexan that already has a suitable diffusion coating? Any help is greatly appreciated! Thanks!

Hi, I have some values that I would like to graph. The x-axis will be Time, and the y-axis will be a sensor reading. My sensor readings are received every 1 second on the UART of a Netduino. Is there a graphing package out there that would fit nicely with the .Net Micro Framework? I would like to display the graph via a Windows form, or via a web page. Any suggestions?

I guess it doesn't really have to be .Net. I've decided to use this for now: XML/SWF Charts

A relay works. The problem is that the relay contacts are not going to last very long if I use this method. Can anyone think of any other way to do this?

Netduino touches my iPad.

See video action here: Netduino triggers iPad Drums. The ticking sound is not a metronome- it is the 9vdc relay I'm using to open and close the Ground.

I also notice that if I increase the speed, sometimes it misses hits on the touchscreen. Does anyone know why? Other than the anti-static foam, should I use other materials to get a more reliable contact?

Just so you know what I need to do:

• Connect anti-static foam directly to the display of an iPad (the anti-static foam is the stuff that IC's are normally mounted on when shipped)
• Connect a wire from Ground to the anti-static foam
• Trigger the Ground connection on and off

This makes the Netduino "touch" the iPad touchscreen. I've already tested this simple scenario and it works, but I have to physically touch the wire to Ground and remove it. I need some way of doing this with Netduino programming.

I have an iPad drums application, and my current idea is to make an automatic drum sample controller with the Netduino;

• Connect anti-static foam to each drum kit point on the iPad display
• Connect separate Grounds for each wire
• Trigger these wires individually so I can press each drum-kit item separately (high-hats, cymbals, bass drum, etc.)
• Record and play back the drum sample on the Netduino, sort of like one of those pianos that plays automatically.

This would also allow me to trigger the drum kit with other materials by using pressure sensors. Ultimately, I could use regular drum sticks on other materials to play the electronic drum kit on the iPad.

The problem I'm solving with this: the iPad display is small, and obviously I cannot smack real wooden drum sticks directly onto the iPad display, so I have to use my fingers to play the drum kit, which is not true to a real drum set, and it is cumbersome.

This would open up the ability to create a small electronic drum kit that could be played with real drum sticks. All the sounds are already there on the iPad; I just need to implement the electronic connections to "touch" the iPad display.

What do you think? Dumb idea? Cool idea? Useless idea?

Has anyone done anything like this before? Any tips?

Thanks!

Darrin, I tried OutputPort, and nothing. I tried TriStatePort, and it triggered a couple of times, but not reliably. I'm going to try a relay now. Thanks, Nick

With Netduino, how can I connect a single wire such that I can switch whether or not the wire is going to ground? Would I use a transistor? The wire does not need any voltage connection- it is just a grounded/un-grounded wire depending on whether I "switch" it between grounded or un-grounded. The other end of the wire is not connected to anything. Thanks!

Nice job, that's awesome!

Next thing I'd try would be a SSR (Solid state relay), something like this: https://www.jameco.c...ductId=1583068

Thanks again Darrin! My local shop doesn't carry SSR's, but they do have 5V Reed Relays, so while I'm waiting for the SSR's, I'll give them a try.

I am trying to find a suitable component that would allow me to measure the brightness of an image appearing on a computer monitor. Specifically, the computer is set up to flash different colored images and I want my Netduino to read and interpret the brightness values of those images. I bought this light-to-frequency converter: http://www.sparkfun.com/products/9768, which looks promising. Does anyone have any other suggestions for suitable components? I suppose I could use a standard photodiode, but I am looking for a large resolution, and I need a fast response time because the colors on the monitor will flash on and off quickly. I am thinking that having a large resolution will allow me to set up a larger range of commands that could occur depending on the light frequency that the Netduino reads. The end goal is to be able to allow a user to program certain aspects of my Netduino using the variances of light frequencies coming from images on a web page. In effect, a "'dark" frequency might represent a "1", and a "light" frequency might represent a "0". A company called Aniomagic has an e-textile product called "Sparkle" that allows you to program it by holding it up to your computer monitor, but I have much bigger plans for this basic idea. You can see "Sparkle's" program page here: http://www.aniomagic...program/?hl=en. Do you think the light-to-frequency converter would work for a Netduino project like this?

Ok, this code works, using the wiring method I mentioned in my other reply above:

using System;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using Microsoft.SPOT;
using Microsoft.SPOT.Hardware;
using SecretLabs.NETMF.Hardware;
using SecretLabs.NETMF.Hardware.NetduinoPlus;

namespace TSL235R
{
    public class Program
    {
        // Constants
        const ulong period = 10000;			   // Number of light frequency measurements
        const float area = 0.0092F;			 // Sensing area of TSL235R device (cm2)
        // Variables
        static ulong pulses = 0;		  // Counter of measurements of the TSL235R
        static ulong frequency;		   // Read the frequency from the digital pin (pulses/second)
        static float irradiance;			    // Calculated irradiance (uW/cm2)

        private static InputPort TSL235R_Pin = new InputPort(Pins.GPIO_PIN_D7, false, Port.ResistorMode.Disabled);

        static int readCount = 0;
        static bool result = false;
        static bool prev_result = false;
        public static void Main()
        {
            while (true)
            {
                while (readCount < 10000)
                {
                    result = TSL235R_Pin.Read();
                    if (result == true && prev_result == false) // Rising
                        pulses++;
                    if (result == false)
                        prev_result = false;
                    if (result == true)
                        prev_result = true;          
                    readCount++;
                }
                getfrequency();			    
                Debug.Print("Frequency:  ");
                Debug.Print(frequency.ToString() + " pulses/second");		 
                getirradiance();			  
                Debug.Print("Irradiance: " + irradiance.ToString() + " uW/cm2");		
                readCount = 0; 
                pulses = 0;		
               Thread.Sleep(1000);        
            }
        }

        static ulong getfrequency () {
            frequency = pulses/(period/10000);    // Calculate the frequency (pulses/second)
            return (frequency);
        }

        static float getirradiance()
        {
            irradiance = frequency / area;	// Calculate Irradiance (uW/cm2)
            return (irradiance);
        } 
    }
}

Example results from debug console:

Frequency:  
1786 pulses/second
Irradiance: 194130.438 uW/cm2
Frequency:  
1790 pulses/second
Irradiance: 194565.219 uW/cm2
Frequency:  
1932 pulses/second
Irradiance: 210000 uW/cm2
Frequency:  
2375 pulses/second
Irradiance: 258152.172 uW/cm2
Frequency:  
2478 pulses/second
Irradiance: 269347.812 uW/cm2
Frequency:  
2640 pulses/second
Irradiance: 286956.5 uW/cm2
Frequency:  
2435 pulses/second
Irradiance: 264673.906 uW/cm2
Frequency:  
3001 pulses/second
Irradiance: 326195.656 uW/cm2
Frequency:  
2720 pulses/second
Irradiance: 295652.156 uW/cm2
Frequency:  
2540 pulses/second
Irradiance: 276086.938 uW/cm2
Frequency:  
2104 pulses/second
Irradiance: 228695.641 uW/cm2
Frequency:  
2742 pulses/second
Irradiance: 298043.469 uW/cm2

There are two problems here though:

• I am not using an InterruptPort, because it did not work properly for me.
• I do not know if the readings I am getting are really accurate irradiance measurements.

Regarding Point 1, if anyone knows how to modify this code to use an InterruptPort, please reply and let me know. I tried to add InterruptPort code, but it causes my Netduino to lock up and become non-responsive to my C# IDE.

Regarding Point 2, I put a black piece of felt cloth over the sensor, and the reading went way down. I then shined a bright light onto the sensor and the reading went way up, so I know I am getting semi-valuable readings. However, the readings fluctuate by about 20 to 50 values while I am at a particular light level, and I am uncertain why. The readings do go up and down as expected, but they also "jump" while they are within that range. How can I fix this? Perhaps there is nothing wrong. I wonder if shadows are causing the "jumps".

Yes, if an Arduino can interface with this sensor, I find it hard to believe that a Netduino cannot.

This is the wiring I am using right now:

TSL235R ------ Netduino
======= ---- ========
GND(1) ---- GND
Vcc(2) ------ +5V
Out(3) ------ Digital I/O pin 2

I also have a 0.1uF cap wired from Vcc to GND, as mentioned in the TSL235R datasheet.

This does not work, and when I try to load my C# via USB, it says: "An error occurred: Please check your hardware." Edit: If I remove the TSL235R from the Netduino, I do not get the hardware error. I have no other devices plugged in to the Netduino.

I also tried wiring it to 3.3V on the Netduino and that does not work either.

Does anyone know what is wrong with my wiring?

I am under the impression that I can use an InterruptPort on the Netduino without the need for additional components. Perhaps code like this would work with the TSL235R? I will give it a try and let you know the results.