That is pretty cool. Small and cheap enough to install in a dedicated project . This definitely gives me some ideas. Watch out

Chris,
Thanks for looking into this. If you change to use ReadToEnd() the behavior is the same. So this might be memory leak inside the StreamReader itself.

I'm getting exactly the same error as Szymon when I try to read a file from the SD card. I actually wrote my sample before I saw this thread, but my code is almost the same.

Here's the sample code where I use a StreamReader object to get the first line of a text file:

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

namespace SDCardSample
{
    public class Program
    {
        public static void Main()
        {
            string currentDir = Directory.GetCurrentDirectory();
            Debug.Print("Current directory: " + currentDir);

            string[] dirs = Directory.GetDirectories(currentDir);
            foreach (string d in dirs)
            {
                Debug.Print("dir: " + d);
                string[] files = Directory.GetFiles(d);
                foreach (string f in files)
                {
                    Debug.Print("file: " + f);
                    StreamReader reader = new StreamReader(f);
                    Debug.Print(reader.ReadLine());
                    reader.Close();
                }
            }
        }
    }
}

And the exception that gets thrown:

Current directory: \
dir: \SD
file: \SD\FOO.TXT
Failed allocation for 685 blocks, 8220 bytes

Failed allocation for 685 blocks, 8220 bytes

    #### Exception System.OutOfMemoryException - CLR_E_OUT_OF_MEMORY (1) ####
    #### Message: 
    #### System.IO.StreamReader::ReadLine [IP: 000a] ####
    #### SDCardSample.Program::Main [IP: 005e] ####
A first chance exception of type 'System.OutOfMemoryException' occurred in System.IO.dll
An unhandled exception of type 'System.OutOfMemoryException' occurred in System.IO.dll

Note that this happens for both ANSI and UTF-8 encoded files (I created the files on the PC).

We have posted updated firmware to address the SD card mounting and memory allocation issues.
http://forums.netdui...patch-4-beta-1/

SD card-related updates in the firmware update:
* Mounting invalid MicroSD cards now throws an exception
* Reduced memory usage when accessing SD cards

Please let me know if this new firmware fixes things for you...

Chris

Cool - thanks for getting the new firmware out so quickly!

This seems to fix the problem I was having with the StreamReader.ReadLine() method yesterday:

Current directory: \
dir: \SD
file: \SD\FOO.TXT
The quick brown fox jumps over the lazy dog.

Now I need to figure out what to do with 1.83 GB of storage.

Chris,

I have no microSD atm, so will need to buy one. Could you post a list of cards that are known to work?

I bought this one today, and it seems to work (well, I can read the directories and file names, but there seems to be a problem with reading file contents).

SanDisk Mobile microSD Card 2GB

$9.99 at Office Depot in the US.

I'd say it also depends a lot on the type of solder you're using. I learned to solder back when Pb/Sn solder wasn't considered hazardous , so my soldering habits have developed around that. I've found that about 350C works well for eutectic (63% Sn, 37% Pb) solder. I just recently started using lead-free solder, and found that I had to kick the temperature up to nearly 400C to get it to melt in a reasonable amount of time, and for it to wet/flow well. Maybe I just haven't gotten used to it yet, but I find the lead-free stuff harder to work with, and the joints never look nice and shiny like Pb/Sn. Instead, the joints have that slightly dull finish, which always makes me worry that I've got a cold solder joint.

Just curious...when you received and opened your Netduino, what were your first impressions?

Anything we can do better to improve the "unboxing" experience?

I just received mine this weekend from the Maker Shed. I'm not sure exactly when it arrived, since I was out of town this weekend, but it was waiting patiently for me in the mailbox when I got home Sunday evening.

Around 9:00 PM I finally got a chance to open the box. I had ordered another item from Maker Shed, and at first I thought the Netduino had been back-ordered. After looking closer, I saw its little black anti-static bag with the blue label.

It's a little smaller than I expected (exact same footprint as Evil Mad Science's Diavolino board). I also found the little rubber feet and the tag, but I don't have a phone that will read it

I got VS2010 Express installed on my machine, then the .NETMF, and finally the Netduino package. I jumped right into the blinkenlight tutorial, and plugged in the Netduino. FWIW, mine didn't come with the micro-USB cable, but I have plenty from other devices, so it wasn't a show stopper for me.

At first, Win7 didn't install the driver - then I closed VS2010, unplugged and re-connected the Netduino, and the drivers installed fine.

Then I deployed the project to the board, and basked in the glow of the blinking blue light .

I must say, it's a better OOBE than my recent foray into the Arduino world (about a month ago). Arduino is cool and all, and I'm sure in many ways it made the Netduino possible. But the Arduino tools feel hacked together, and I've spent way more time futzing around with the tools than actually working on hardware.

This is what Arduino should have been, IMO. Leveraging Visual Studio, .NET MF, and C# was an inspired choice. It puts professional-quality development tools in the hands of hobbyists and startups.

This is very cool, and I can't wait to spend more time playing with it.

Have you tried to enable glitch filter: button = new InterruptPort(..., true, ...) ? The debouncing time is controlable via CPU.GlitchFilterTime [^] property.

I haven't tried the Glitch filter yet, thanks for the suggestion.

Do you happen to know what the default glitch filter time is (or what value is appropriate to debounce a pushbutton)?

I have playing with the example on my silly emulator and works great

http://forums.netdui...indpost__p__277

Cool, thanks! I've been meaning to try out your emulator. So many projects, so little time...

OK, here's my ToggleButton sample from the other thread "Using InterruptPorts".

This is basically like the Event Handlers tutorial on the Projects page. The main difference is that the pushbutton acts like a toggle - push once to turn off the LED, then push again to turn it back on.

Another slight modification - the interrupt handler method calls DisableInterrupt() at the start of the method, and EnableInterrupt() at the end. This seems to fix an issue where pressing and holding the button would sometimes cause the LED to change state when the button was released.

I think this might be due to switch bounce, so multiple interrupts were getting "stacked up" and handled after the first interrupt method returned.

Anyway, here's the code. Let me know if there's interest in posting the entire VS solution. Enjoy!

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

namespace ToggleButton
{
    public class Program
    {
        static bool ledState;
        static InterruptPort button;
        static OutputPort led;

        public static void Main()
        {
            // Set the initial state of the LED to on (true).
            ledState = true;

            led = new OutputPort(Pins.ONBOARD_LED, ledState);

            button = new InterruptPort(
                Pins.ONBOARD_SW1, 
                false, 
                Port.ResistorMode.Disabled, 
                Port.InterruptMode.InterruptEdgeLow);

            // Bind the interrupt handler to the pin's interrupt event.
            button.OnInterrupt += new NativeEventHandler(SwitchInterruptHandler);

            while (true)
            {
                Thread.Sleep(Timeout.Infinite);
            }
        }

        public static void SwitchInterruptHandler(UInt32 data1, UInt32 data2, DateTime time)
        {
            button.DisableInterrupt();

            // Invert the previous state of the LED.
            ledState = !ledState;

            // Set the LED to its new state.
            led.Write(ledState);

            // Un-comment the following line if using level interrupts.
            // button.ClearInterrupt();

            button.EnableInterrupt();
        }

    }
}

Hi Shane and welcome!

The Debug.Print will appear in the Output window within Visual Studio or Express.

Cheers,
Matt.

And you need to have the debugger attached. In VS2010, go to Debug | Start Debugging, which will run the solution in the debugger.

If the debugger isn't attached, the Debug.Print() statements will have no effect.

You can also view the Debug.Print statements through MFDeploy. If you're not running the app from Visual Studio, press F5 in MFDeploy to hook into the Netduino's Debug output.

Chris

Oh, cool - I didn't know that. Thanks for the tip!

Removing the rest of the evidence

klotz,

A bit of both. But mostly a software limitation. If there's interest, we can start a community project to expand this to 4GB or beyond (for MicroSD cards that support SPI).

Chris

As a member of the community, I'd be interested in the project to expand the microSD capacity...

I quite like flying things. Will it be a flying rug? Only time will tell

Flying rugs are so old world. I vote for flying cars

Would you be interested in helping implement (Micro)SDHC libraries using SPI?

Sure.

Helping lead the team?

Uuhm, depends on what you mean by "team".

Sorry, I'm voluntarily deleting my previous remark, since it was somewhat inappropriate. I don't mean to detract from the Secret Labs announcement.

Just out of curiosity, do you plan to extend PWM control to compensate the LED brightness non-linearity?

Hi CW2,

Thanks for the suggestion - I think that would be a good follow-on sample. For the time being, I just wanted to create something equivalent to the Arduino "Fading" sample, but showcase some of the Netduino / NETMF features (like timer callbacks, and a "real" Sleep() function).

The Arduino sample also just folows a linear PWM ramp, which as you mention, doesn't correspond to a linear brightness at the LED

A more advanced exercise might use a lookup table to compensate for the non-linear response of the LED.

BTW, does anybody happen to know what the response curve of a typical LED looks like? I'm curious if it's a logarithmic function (like audio), or if it's something completely different.

Hi Netduino fans,

Here's a little sample that uses a PWM pin to control the brightness of an LED. I like to call it PwmSample, for lack of a better name.

What it does:
When you press and hold the pushbutton, a connected LED will gradually brighten and dim. If you release the pushbutton, the LED stays at its current brightness. Pushing the button again will resume the brighten/dim cycle from the current value.

How it works:
This sample combines several techniques from the previous samples. It uses an InterruptPort for the pushbutton input; the SwitchInterruptHandler() method is called when the InterruptPort detects a rising or falling edge due to the pushbutton.

The sample also uses a Timer callback to do the actual LED brightness control. Every 20 milliseconds, the PwmTimerCallback() method is called. This method checks whether the pushbutton is closed (the buttonState variable). If so, then it increments (or decrements) the PWM pin's duty cycle.

Circuit:
Note that you'll need to connect an external LED to the Netduino board (it won't work with the built-in LED, since it's not connected to a PWM-enabled pin).

I used Digital Pin 5 in the sample; you can use any PWM-enabled pin (5, 6, 9, or 10), but make sure to change the Pin definition on line 34.

I don't have a schematic editor handy, but the circuit is simple enough. Just connect one end of a 100-ohm resistor to Digital Pin 5. Connect the other end of the resistor to the anode (+) lead of your LED. Then connect the cathode (-) lead of the LED to one of the GND pins on the Netduino Power header.

Here's the code:

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

namespace PwmSample
{
    public class Program
    {
        const int pwmPeriod = 20;
        const uint MaxDutyCyle = 100;

        static bool buttonState;
        static int pwmDutyCycle;
        static int pwmIncrement;
        static InterruptPort button;
        static PWM led;

        public static void Main()
        {
            pwmDutyCycle = 0;
            pwmIncrement = 1;
            buttonState = false;

            // NOTE: You will need to connect an LED to Digital Pin 5 on the Netduino board.
            // Use a 100-ohm (brown-black-brown) resistor between the LED anode (+) and Digital Pin 5.
            // Connect the LED cathode (-) to one of the GND pins on the Power header.
            //
            // You can use any other PWM-enabled pin (5, 6, 9 or 10), but also remember to change
            // the Pin parameter in the PWM constructor below.

            led = new PWM(Pins.GPIO_PIN_D5);

            button = new InterruptPort(
                Pins.ONBOARD_SW1,
                false,
                Port.ResistorMode.Disabled,
                Port.InterruptMode.InterruptEdgeBoth);

            // Bind the interrupt handler to the pin's interrupt event.
            button.OnInterrupt += new NativeEventHandler(SwitchInterruptHandler);

            // Create a System.Threading.Timer instance and pass it the timer callback method.
            Timer pwmTimer = new Timer(
                new TimerCallback(PwmTimerCallback),
                null,
                pwmPeriod,
                pwmPeriod);

            Thread.Sleep(Timeout.Infinite);
        }

        public static void PwmTimerCallback(Object obj)
        {
            // Only change the LED brightness when the button is pushed (true).
            if (true == buttonState)
            {
                // Set the pin's new duty cycle.
                pwmDutyCycle += pwmIncrement;
                led.SetDutyCycle((uint)pwmDutyCycle);

                Debug.Print(pwmDutyCycle.ToString());

                if ((MaxDutyCyle == pwmDutyCycle) || (0 == pwmDutyCycle))
                {
                    // The duty cycle has hit the min or max value.
                    // Start ramping in the other direction.
                    pwmIncrement = -pwmIncrement;
                }
            }
        }

        public static void SwitchInterruptHandler(UInt32 data1, UInt32 data2, DateTime time)
        {
            button.DisableInterrupt();

            buttonState = (0 == data2);

            button.EnableInterrupt();
        }

    }
}

Oooooooooooooo... button-controlled fading. Pretty!

Now to get my head around the code and get it doing something useful.

dab, thanks for publishing useful example. How do you suggest I get a relevant basic command reference? I hate reading (and writing) documentation as much as the next guy but there are times when it really helps...

The community (including me ) would probably benefit enormously from some pointers on how to research the command syntax.

Hi FastEddy,

Thanks for the kind words - I'm glad you find the sample code helpful .

You raise a good point about getting up to speed on the technology. I consider myself pretty much a newbie to C# and the .NET framework (until relatively recently, I was a C++/Win32 API kind of guy).

For me, the biggest challenge is the .NET framework itself. It's huge (even .NETMF), and a lot of classes aren't very discoverable. I always find myself thinking "I know there's a class/method to do 'x', but where?".

Here are some things I've found helpful:

• Sample code. Find something here in the Project showcase that looks interesting to you, get the source code, and play with it. Look up the classes / methods that you're not familiar with. Try making small changes to the code and see what happens. Don't be afraid to experiment.
  
• Online documentation. Currently, the best available documentation is at the MSDN library site. But be aware that even that is sometimes wrong, or slightly out-of-date for the .NETMF libraries.
  
• Books. There are a couple of books that I've found sort of useful. One is "Embedded Programming with the .NET Micro Framework", by Donald Thompson and Rob Miles. The other is "Expert .NET Micro Framework" by Jens Kuhner. Both of these are a bit dated, but have some useful sample code. There's also quite a bit of stuff in both books that I didn't find that useful, but they're worth reading for a couple of chapters (I'd recommend borrowing them if you can find a library that has them, or buy used copies).
  
• Community. Right here is a good resource - it's a fairly small (but growing) community, and people I've seen are eager to share and swap advice and ideas. And the Secret Labs folks here are also super-helpful.

I hope that helps get you started.

Nice usage of interrupt handler parameter (data2) to get the pin/button state.

Thanks, Chris. To give credit where it's due, I plagiarized copied that from the Event Handlers tutorial.

TBH, I couldn't find much in the way of documentation of how data1 and data2 are used in the callback. The .NETMF documentation mentions that data1 is the port, and data2 is the state, but "state" in this context was a little unclear. Apparently it refers to the logic state of the pin that generated the interrupt, but having that documented explicitly might be a good thing

A more advanced exercise might use a lookup table to compensate for the non-linear response of the LED.

BTW, does anybody happen to know what the response curve of a typical LED looks like? I'm curious if it's a logarithmic function (like audio), or if it's something completely different.

I did a little research to answer my own question.

It appears that LEDs have a gamma relationship between the voltage and perceived brightness. I found this application note that explains it nicely:

http://www.maxim-ic....dex.mvp/id/3667

So, I've posted an updated version of the PwmSample (under the "PwmGamma" topic in this forum) that uses a LUT (lookup table) to implement the gamma correction.

The PwmGamma sample ramps the LED brightness in a way that looks more linear (still not perfect, but much better than before).

How about a "Netduino Projects" forum where users can showcase their projects?

And then the Sandbox would be perfect for posting code snippets?

Sounds good!

Do you intend for this forum to be used as a place for examples or mostly just troubleshooting of the main board? Cause I'm always writing and posting my *duino examples and I'd love to post them here (once my netduino shows up) if there were some Examples/Tutorials section that users could post to. Thanks, the product sounds like it should be a hoot and a half.

+1 to this suggestion. I think a place to share code and examples would be a good idea.

Thanks, Chris, I'll take a look at the mftoolkit. Worst case, I suppose it probably wouldn't be too difficult to port an existing Arduino XBee library (although I haven't seen the source code). Thanks!

Hi folks,

I'm also very excited about the Netduino and the .NET goodness that it brings to the AVR microcontrollers .

Along the same lines as nirav's question - is there (or will there be) support for the XBee wireless Arduino shields?

For example:
http://www.sparkfun....roducts_id=8664

Thanks, and I can't wait until my Netduino board arrives!