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dab's ContentThere have been 54 items by dab (Search limited from 06-July 24) #58 Arduino wifi sheilds.
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! #82 Arduino wifi sheilds.
#64 Arduino wifi sheilds.
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!
#487 BlinkyTimer sample
You beat me to it.  Thanks again, Chris! (And get some sleep, OK?) #478 BlinkyTimer sample
Here's another little sample that I put together called BlinkyTimer.
This basically does the same thing as the Blinky tutorial, but it uses a Timer object with a callback method to turn the LED on and off. Here's the code. If you think of any cool variations, please share. 
using System;
using System.Threading;
using Microsoft.SPOT;
using Microsoft.SPOT.Hardware;
using SecretLabs.NETMF.Hardware;
using SecretLabs.NETMF.Hardware.Netduino;
namespace BlinkyTimer
{
public class Program
{
const int blinkPeriod = 250;
static bool ledState;
static OutputPort led;
public static void Main()
{
// Set the initial state of the LED to off (false).
ledState = false;
led = new OutputPort(Pins.ONBOARD_LED, ledState);
// Create a System.Threading.Timer instance and pass it the timer callback method.
Timer blinkTimer = new Timer(
new TimerCallback(BlinkTimerCallback),
null,
blinkPeriod,
blinkPeriod);
Thread.Sleep(Timeout.Infinite);
}
public static void BlinkTimerCallback(Object obj)
{
// Invert the previous state of the LED.
ledState = !ledState;
// Set the LED to its new state.
led.Write(ledState);
}
}
}
#483 BlinkyTimer sample
Thanks Chris! And thanks for moving it to the new forum.
Yeah, I keep meaning to fix that. It was in a sample program from the book "Embedded Programming with the Microsoft .NET Micro Framework", but I agree it seems redundant. It might also make the code a little smaller by removing the while loop(?). #3129 Buying or Acquiring Parts
This is a timely topic
. It would nice to make this a sticky thread for future reference (and a place to point somebody to when they ask where to find things).I'll add a couple more:
#3237 Console Output??
Oh, cool - I didn't know that. Thanks for the tip! #3209 Console Output??
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. #2602 Controlling a LED Intensity
And if you have any questions about the PwmSample, please feel free to post them here or in the Project Showcase forum (I posted the sample code).
Let us know when you get the Cylon / Knight Rider circuit working (and share the code if you don't mind).
#1404 Electronics Books
+1 on Make: Electronics. Very fun and easy read, with clear explanations and experiments that demonstrate the principles well. Some of the old Radio Shack books by Forest M. Mims are also quite good. I believe you can still get his classic "Getting Started in Electronics", as well as reprints that combine several of the small "Engineer's Mini Notebook" titles in one book. #476 Facebook
I think you guys need a facebook page...
#3261 How to use the SD card and StreamWriter
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. 
#3178 How to use the SD card and StreamWriter
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). #470 I love this thing, maybe too much...?
Yep, generally PC fans are available in the following flavors:
2 wires: Constant speed 3 wires: Constant speed w/ tachometer output 4 wires: Variable speed w/ tachometer output and speed input (PWM) I recently saw an article on the Make: blog where a guy had connected a 3-wire fan to an Arduino and it displayed the fan's speed on 7-segment displays. I think that would be a good re-make with the Netduino. http://blog.makezine...th_arduino.html #627 InterruptPort
Or maybe you could award Fabulous PrizesTM to the top bug finders (like a Netduino board or a trip to Hawaii).
#566 InterruptPort
Cool, I'll be sure to try it out (tomorrow). #441 InterruptPort
Hi xc2rx, I found the same thing that you did with the glitchFilter parameter. (BTW, I'm the guy who posted the ToggleButton sample that Chris referred to). In the ToggleButton sample, if I set the InterruptPort's glitchFilter parameter to true, it seems that the interrupts don't fire (or the event associated with the interrupt doesn't fire - not sure which one). @Chris - is there a way we can investigate this further? #3180 Introducing Netduino Plus -- Notes
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. #2702 Out of memory error
I think we'd need to see the rest of the code in order to find the problem. Can you post the complete source code?
#3236 Power Questions - i.e. Voltage
Well, you could put two of the 6V batteries in series to get 12V. With a regulator, it's fairly easy to *decrease* the voltage. But, in general, it's not easy to increase the voltage of a DC source. Increasing the voltage generally involves converting DC to AC (or a DC square wave), passing it through a step-up transformer, and converting back to DC. But if you do that, then the current will decrease proportionally with the voltage increase (actually, you'll lose even more current due to losses in the transformer, etc.). #1400 Pwm2Color Sample
Hi Netduino fans,
Here's a fun little project that builds on my previous PwmSample and PwmGamma programs. The Pwm2Color sample controls a 2-color LED (or 2 individual LEDs, if you wish). It uses 2 pushbutton switches as input; one button controls the intensity of the Red LED, and the other button controls the Green LED. The buttons gradually ramp the LED intensity up and back down, using Gamma correction to make the ramps more linear. By using a 2-color LED (which is just 2 LED substrates in the same package), you can mix the red and green components in different proportions, creating intermediate shades of yellow and orange. Please see the comments in the code for a description of the circuit. I'll try to post up a schematic later if there's interest. I've made a few tweaks since the PwmGamma sample, and tried to streamline the code a bit:
using System;
using System.Threading;
using Microsoft.SPOT;
using Microsoft.SPOT.Hardware;
using SecretLabs.NETMF.Hardware;
using SecretLabs.NETMF.Hardware.Netduino;
namespace Pwm2Color
{
// The Channel class encapsulates the PWM port for an LED, the InterruptPort
// for the corresponding pushbutton switch, and some state variables.
public class Channel
{
public bool ButtonState { get; set; }
public int PwmIndex { get; set; }
public int PwmIncrement { get; set; }
public PWM Led
{
get { return _Led; }
}
private PWM _Led;
public InterruptPort Button
{
get { return _Button; }
}
private InterruptPort _Button;
public Channel(Cpu.Pin LedPin, Cpu.Pin ButtonPin)
{
ButtonState = false;
PwmIndex = 0;
PwmIncrement = 1;
_Led = new PWM(LedPin);
_Button = new InterruptPort(
ButtonPin,
true,
Port.ResistorMode.Disabled,
Port.InterruptMode.InterruptEdgeBoth
);
}
}
public class Program
{
const int pwmPeriod = 50;
const uint MaxDutyCyle = 100;
// Lookup table for the LED brightness. The table contains the
// gamma-corrected values (for gamma = 2.5). This approximates
// a linear increase in the perceived brightness.
//
// Declaring it as a byte array makes the assembly a little smaller,
// and the byte values automatically get promoted to uint when
// setting the PWM duty cycle.
static byte[] gammaTable = {
0, 0, 0, 0, 1, 1, 1, 2, 2, 3,
4, 5, 6, 7, 9, 10, 12, 14, 16, 18,
20, 22, 25, 28, 31, 34, 37, 41, 45, 49,
53, 57, 62, 67, 72, 77, 82, 88, 94, 100,
};
static Channel[] channels;
public static void Main()
{
// NOTE: You will need to connect 2 LEDs and an additional pushbutton switch
// to the Netduino board. The circuit is as follows:
//
// 1. Connect a 100-ohm resistor between the anode of the Green LED and Digital Pin 5.
// 2. Connect a 100-ohm resistor between the anode of the Red LED and Digital Pin 6.
// 3. Connect the LED cathode(s) to GND on the Power header.
// 4. Connect a 1K pull-up resistor between 3V3 on the Power header and Digital Pin 1.
// 5. Connect one side of the SPST pushbutton switch to Digital Pin 1. (This switch
// controls the Red LED).
// 6. Connect the other side of the SPST pushbutton switch to GND on the Power header.
//
// I used a 2-color LED which has red and green LEDs in the same package.
// Electrically, it's the same as 2 separate LEDs, so the circuit is virtually the same.
// If you use a 2-color LED, be sure to get the common-cathode variety.
// With a 2-color LED, you can "mix" the colors in varying proportions.
// When both red and green are on, the resulting color is yellow or orange.
//
// It should be almost trivial to modify this program to handle a 3-color LED. ;)
// Allocate the array to hold 2 Channel references.
channels = new Channel[2];
// Create each Channel and add it to the channels[] array.
channels[0] = new Channel(Pins.GPIO_PIN_D5, Pins.ONBOARD_SW1); // Green channel
channels[1] = new Channel(Pins.GPIO_PIN_D6, Pins.GPIO_PIN_D1); // Red channel
// Bind the interrupt handler to the pin's interrupt event.
// The same interrupt handler is used for all the channels.
// The data1 parameter in the handler will determine which button
// generated the interrupt.
foreach (Channel ch in channels)
{
ch.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 corresponding button is pushed (true).
foreach (Channel ch in channels)
{
if (true == ch.ButtonState)
{
// Set the pin's new duty cycle.
ch.Led.SetDutyCycle(gammaTable[ch.PwmIndex]);
ch.PwmIndex += ch.PwmIncrement;
Debug.Print(gammaTable[ch.PwmIndex].ToString());
if (((gammaTable.Length - 1) == ch.PwmIndex) || (0 == ch.PwmIndex))
{
// The duty cycle has hit the min or max value.
// Start ramping in the other direction.
ch.PwmIncrement = -ch.PwmIncrement;
}
}
}
}
// port: The pin number of the port that generated the interrupt
// state: The logic state of the port
// time: Time of the event
public static void SwitchInterruptHandler(UInt32 port, UInt32 state, DateTime time)
{
foreach (Channel ch in channels)
{
if (port == (UInt32)ch.Button.Id)
{
ch.ButtonState = (0 == state);
}
}
}
}
}
#807 PwmGamma Sample
You mean you actually take vacation? 
#734 PwmGamma Sample
As a follow-up to the PwmSample, CW2 suggested extending it to address the non-linear response of the LED.
After a bit of research, I found that this is referred to as "gamma correction", and even found an application note that discusses using gamma correction with PWM: http://www.maxim-ic....dex.mvp/id/3667 So, here's an update to PwmSample that uses a pre-computed LUT (lookup table) for the PWM output values. These are the gamma-corrected values (for gamma = 2.5) that produce a brightness ramp that looks linear (more or less) to our eye. 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 PwmGamma
{
public class Program
{
const int pwmPeriod = 50;
// Lookup table for the LED brightness. The table contains the
// gamma-corrected values (for gamma = 2.5). This approximates
// a linear increase in the perceived brightness.
static uint[] gammaTable = {
0, 0, 0, 0, 1, 1, 1, 2, 2, 3,
4, 5, 6, 7, 9, 10, 12, 14, 16, 18,
20, 22, 25, 28, 31, 34, 37, 41, 45, 49,
53, 57, 62, 67, 72, 77, 82, 88, 94, 100,
};
static bool buttonState;
static int pwmIndex;
static int pwmIncrement;
static InterruptPort button;
static PWM led;
public static void Main()
{
pwmIndex = 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.
led.SetDutyCycle(gammaTable[pwmIndex]);
pwmIndex += pwmIncrement;
Debug.Print(gammaTable[pwmIndex].ToString());
if (((gammaTable.Length - 1) == pwmIndex) || (0 == pwmIndex))
{
// 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();
}
}
}
#2601 PwmSample
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:
I hope that helps get you started. | ||||||||||||||
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