If you want to drive more leds this way (up to eight), the uln2803 could be handy.

See it in action with a netduino and an analog input here

Gonna try this, thanks.

I would be cool if the was a way to create a sort analog interrupt port. With a trashhold for a parameter.. if it changes more than the trashhold it will create an interrupt. Is this a good idea for future firmware? Or is this technically impossible?

If the cable is the problem, and you want a cheap solution for converting the signals you could use the TI MAX232. Works for me.

I'm not sure, but I believe the Plus was available for a short time/amount with the resellers. And a selected group of community members got one. It's exactly the same platform as the regular netduino, with the addition of a network connection and a microsd card reader.

Any thoughts experiances on connecting 2 or more netduino's over a 5 meter distance? I have no idea, and was thinking of an ethernet shield, is that a good idea? Is there something better/cheaper? Thanks

Just use a XBee wireless. It's straight serial comm through the UART so it's easy.

Thanks but,

forgot to mention: I want it te be wired, not wireless. And I want to connect 3 or more..

The I2C on the ARM7X chip is master-only. We'll see what we can do on speeding up Ethernet support...

Chris

That would be realy cool. Would even do greater distances and could use a switch for connecting them..

Yes. Unlike AVRs, Netduino cannot drive 20~30 mA LEDs directly. Depending on your intended usage, it may be sufficient to drive the LED with only 15 mA, it will be a bit dimmer, or you can use LEDs for smaller current (2 - 10 mA).

Please note Netduino has only three pins that can draw 16 mA (D3, D4, D7), analog pins can draw only 2 mA in digital mode, the rest of pins can draw only 8 mA.

Okay. What would be the simplest schematic and/or component to use, if I want to make sure I don't wreck my netduino connecting the outputs to stuff drawing more than those mA's?

Thanks.

I just want to connect a number of 50mA leds. Will any transistor do then? And does something like 8 transistors in a IC package exist, so I can connect them to all my outputs and connect 8 leds?

Yes, any general purpose transistor like BC54x (Ic = 100 mA) or 2N4401 (Ic = 600 mA) will be fine. I often use ULN280x Darlington array (Ic = 500 mA) or serial-in/parallel-out shift register 74HC595 (20-35 mA, various derivatives) to drive multiple LEDs (matrices).

However, there are still a few other things to consider, for example 8*50 mA = 400 mA, which is close to the limit a USB port can provide (500 mA) and I think I have seen in the firmware source code that Netduino is configured at only 280 mA (have to verify this), so you may not be able to power the Netduino and LEDs from the USB port, an external power supply would be required. And, if you are driving the LEDs by PWM or multiplexing, the peak current can be significantly higher, so you'd need to account for it when selecting the components.

This is why I (annoyingly) ask for details, in my experience "connecting a LED" can mean anything from multiplexed 16*16*16 cube to 20 W RGB power LED...

Just for playing around and testing. Ordered myself a ULN2804. Thanks

For LEDs and the like, you should be fine as-is. If you have the chance to buy a 3.3V version of a component rather than a 5V version of the component, you'll generally want to do so.

The most important case is with communication protocols (SPI, I2C, UARTs, etc.) Many components can take either 3.3V or 5V, but some are more particular.

If in doubt, feel free to ask questions about particular parts here... There are a lot of people with electronics experience in the community.

Chris

Isn't a 5mm led using about 30mA, so too much for directly to the digital outs which can supply only 16mA?
Shouldn't we use a driver of some sort ?

I'm experimenting with the code I posted earlier:

using System; 
using System.Threading; 
using Microsoft.SPOT; 
using Microsoft.SPOT.Hardware; 
using SecretLabs.NETMF.Hardware; 
using SecretLabs.NETMF.Hardware.Netduino; 
using Microsoft.SPOT.Net.NetworkInformation; 
using Microsoft.SPOT.Net; 
using System.Net.Sockets; 
using System.Net; 
using System.Text; 
 
namespace NetduinoApplication2 
{ 
    public class Program 
    { 
 
        public static void Main() 
        { 
 
            using (System.Net.Sockets.Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp)) 
            { 
 
                IPHostEntry entry = Dns.GetHostEntry("192.168.5.111"); 
                IPAddress address = entry.AddressList[0]; 
                IPEndPoint endpoint = new IPEndPoint(address, 80); 
 
                socket.Connect(endpoint); 
                socket.Send(Encoding.UTF8.GetBytes("Hallo Netduino plus")); 
            } 
 
        } 
 
    } 
}

This works.. I'v got IIS running on my notebook, and i'm seeing this in my logfiles:

2010-09-25 07:39:58 192.168.5.150 4098 192.168.5.111 80 - Hallo Netduino 400 - BadRequest -

Which is expected.


However, if I change the ip address in the code above to a non existant address (like 192.168.5.10)..just to test what happens.. this totally crashes the netduino plus and VS 2010. Only way to recover is to reset the netduino with the reset button.

Am I just the wrong code? or is this a bug?

If you try to connect to a non-existant address, it's possible that lwIP has a timeout of "infinite" and will just never stop trying Or it's possible that there's a bug in there. .NET MF is using interop with networking, and any native code (i.e. lwIP's socket connect routines) that don't return could cause Visual Studio to wait and wait and wait... There is room to improve this--and this is great feedback to start down that path.

If I understand it right, connecting to a good address is successful--and you can easily recover by pressing the reset button on the Netduino Plus--correct? That's a good backup plan for now.

We'll look at timeout values and see what we can do to make it throw an exception quickly rather than wait forever...

Thank you very much for the feedback!

Chris

Yes, connecting to a existant address works fine. And yes, I can recover using the reset button.
I timeout would be nice, I would expect and exception.

Hi Dallas,

Amazon should have more Netduinos in stock soon. That said, I would not hesitate to buy from MakerSHED or Proto-Advantage...they should both be able to take good care of you.

And...welcome to the Netduino community. Thanks for posting!

Chris

Good experiance with Makershed here, shipped in 1 day nicely packaged. And 'adjusted' the value for customs.

Are you sure that your relay module is suited for the netduino with regards of the current that can/will be drawn?

Have you tested it just with a volt meter with nothing connected? This behaviour could be caused by other connected components.

Are you using an external power supply? If so, are you sure all the gounds are connected?

You don't state this directly.. but this would allow upgrades by network, right?

Sorry, I guess it is not totally done yet..

See here

I know there is a firmware with which you can debug over serial, and use the usb as you want. But never used it.

I've setup a small program to measure the performance of the netduino:

    public class Program
    {
        static bool state = false;
        static OutputPort led = new OutputPort(Pins.ONBOARD_LED, false);
        static AnalogInput input1 = new AnalogInput(Pins.GPIO_PIN_A0);
        static int analogValue = 0;
        static bool ledstate = false;
        static int counter = 0;

        public static void Main()
        {
            long start = DateTime.Now.Ticks;

            for (int i = 0; i < 2500; i++)
            {
                analogValue = input1.Read();
                ledstate = !ledstate;
                counter = counter + 1;
                led.Write(ledstate);
            }

            long end = DateTime.Now.Ticks;
            TimeSpan span = new TimeSpan(end - start);
            Debug.Print("timespan: " +span.Milliseconds.ToString() + "ms");

        }

    }

If I run this code, it reports that it took 37ms. But if I comment out the

counter = counter + 1

part it reports that it took 979ms !! Thats strange right?

I increased the for to about 20000, then it reports it took 900ms, but the led is way longer on than a second. So it simply reports the wrong time. But why? Can't figure it out.

Is there a TimeSpan.TotalMilleseconds like there is in the full .Net Framework? If not you'll need to add all of the components of the timespan after you multiply them out to get the total.

Right. That must be it.. stupid mistake.

I was looking for the Stopwatch Class be couldn't vind it.. so wrote my own (including stupid mistakes)

Thanks

I saw an other forum post about a working LCD by serial. Try the search function.

This one: http://forums.netdui...allax-lcd-test/