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You're most likely NOT going to find example source code for this.
This shouldn't be that hard. Picking the number of bands and the colors for each would probably be the hardest part. After that, it's pretty simple to do the math to get the resistor value.
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this is not a gimme-code site. You can come here and ask specific questions when you tried something yourself and got stuck somehow.
Resistor colors to resistance value conversion is a pretty simple homework assignment. Get to it.
Luc Pattyn [My Articles] Nil Volentibus Arduum
Fed up by FireFox memory leaks I switched to Opera and now CP doesn't perform its paste magic, so links will not be offered. Sorry.
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It's been a while since I've done component-level troubleshooting, but some of those color bands were *very* indistinguishable, especially when the manufacturer made them very thin. I remember browns and purples that were basically the same...
Anyway, interesting program idea. 
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prateek
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how can i handle Datagridview's Keydown Event after editing cell on Enter key Press
datagridview have columns readonly=false and columns readonly=true
need when i press enter key goto cell[6] of next row from any cell in previous row (====> this important one)
and when i press tab from cell [4] call func and tab from other cells call another func
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the answer 
private const UInt32 WM_KEYDOWN = 0x0100;
public bool PreFilterMessage(ref Message m)
{
if (this.ActiveControl is DataGridViewTextBoxEditingControl)
{
if (m.Msg == WM_KEYDOWN)
{
Keys keyCode = (Keys)(int)m.WParam & Keys.KeyCode;
if (keyCode == Keys.Enter)
{
if (this.dgvReadInsert.CurrentCell.ColumnIndex == 4 || this.dgvReadInsert.CurrentCell.ColumnIndex == 10 || this.dgvReadInsert.CurrentCell.ColumnIndex == 6 || this.dgvReadInsert.CurrentCell.ColumnIndex == 12 || this.dgvReadInsert.CurrentCell.ColumnIndex == 13 || this.dgvReadInsert.CurrentCell.ColumnIndex == 14)
this.dgvReadInsert.CurrentCell = this.dgvReadInsert[6, this.dgvReadInsert.CurrentCell.RowIndex + 1];
return true;
}
}
return false;
}
return false;
}
after inherit from
class form1 : Form, IMessageFilter
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I have a situation where I am parsing through a string generated by serialPort1.ReadExisting(). I started getting somewhat random errors, and to troubleshoot this I started writing each value of the string parsing, to a textbox window.
It appears that sometimes the entire stream is not being received, because the length of RxString is changes sometimes and I believe that my errors are caused when only 1/2 of a single value of data I am trying to parse, is received, so that when I'm doing string.indexof, there is nothing left and it is causing "failed StartIndex cannot be less than zero" error message.
Has anyone experienced this before? Or can anyone speculate what I might be doing wrong in my code?
private void serialPort1_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
{
if (serialPort1.IsOpen)
{
RxString = serialPort1.ReadExisting();
this.Invoke(new EventHandler(displayData));
}
else
{
return;
}
}
private void displayData(object sender, EventArgs e)
{
int count = 0;
try
{
count = 0;
if (Regex.Match(RxString, @"\r") != null)
{
RxString = Regex.Replace(RxString, @"\r", "\r\n", RegexOptions.Multiline);
}
if (RxString.Contains("ps2="))
{
count = count + 1;
txtDiagnostic.Text += count + ", ";
int totalLength = RxString.Length;
txtDiagnostic.Text += totalLength + ", ";
int startDelimiter3 = RxString.IndexOf("ps2=");
txtDiagnostic.Text += startDelimiter3 + ", ";
string ps2String = RxString.Remove(0, startDelimiter3 + 4);
int endDelimiter3 = ps2String.IndexOf("\r\n");
txtDiagnostic.Text += endDelimiter3 + ", ";
ps2String = ps2String.Remove(endDelimiter3);
rtbPressureSensor2.Text = ps2String;
txtDiagnostic.Text += ps2String + System.Environment.NewLine;
Application.DoEvents();
}
Thread.Sleep(250);
}
catch (Exception ex)
{
MessageBox.Show("displayData() failed " + count + " " + ex.Message);
}
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Serial communication is just that: data arrives as a stream of databits, some of which are parts of characters, others are framing which wrap the characters and provide a way to identify when they start, stop, and if there are received correctly.
When the bit stream arrives at the hardware, it finds each character one by one and hands that on to the OS software. The software hands it to the .NET framework, which then raises an event to tell you that there is data. While the OS and the framework are doing this, and while your program is sorting itself out to process the character, the databits are still arriving, and still being processed by the hardware into characters - and it is telling the OS each time it has one. So, when your program finally gets allowed to look at the data (and bear in mind that may not be immediately as Windows in a multitasking OS) there could be anything from one character to the whole message waiting for you. If may take one, or many DataRecieved Events to receive the whole message - and the number could be completely different next time you try because what else is going on in the whole system is different.
You can't just look at the currently available data - you have to look at the whole message. Which means you need to buffer it up until you have got to the end of the message, or a suitable amount of time has passed without getting the whole message. if you just read the data into a single string each time you get a DataRecieved event, all you will do is most likely throw away the data you have already got...
Ideological Purity is no substitute for being able to stick your thumb down a pipe to stop the water
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Hi,
Thank you for the reply.
I cannot buffer it until I get everything, as it is a logging function and I believe I could end up hogging too much memory.
What is the best practice for receiving chunks of data and then parsing it? Do I have to have synchronization for this on both my PC and microchip end? I was hoping that if I only streamed updated data every 250mS from the source, that I would not encounter issues like this.
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if the data is text and has a line delimiter (one or two characters that won't appear in the middle of the message), I would not use events at all; I'd rather use a Thread or a BackGroundWorker with an eternal loop, performing a SerialPort.ReadLine() and some output operations. That way you get rid of all worries about partial messages, and you don't need any additional buffering. You should set your definition of the message delimiter explicitly through SerialPort.NewLine[^]
BTW: If the delimiter could vary, say \n or \r\n, then you should set the SerialPort to look for the shorter one, and remove the other character from each line you get.
Luc Pattyn [My Articles] Nil Volentibus Arduum
Fed up by FireFox memory leaks I switched to Opera and now CP doesn't perform its paste magic, so links will not be offered. Sorry.
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I will try and implement that.
Thank you Luc.
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Luc,
I think I tried this one before with SerialPort.NewLine and I did
serialPort1.NewLine = "\n";
serialPort1.NewLine = "\r";
serialPort1.NewLine = "\n\r";
serialPort1.NewLine = "\r\n";
And none of them format correctly, the only thing I was able to get working was that regex?
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turbosupramk3 wrote: I think I tried
great piece of FUD.
you should know what will be received and program for that. Then if something else is received, cope with it.
What you must do is include logging in your code, so you can see what you are receiving.
and it makes sense to log each character in 2-digit hex, so everything is clearly identifiable.
Luc Pattyn [My Articles] Nil Volentibus Arduum
Fed up by FireFox memory leaks I switched to Opera and now CP doesn't perform its paste magic, so links will not be offered. Sorry.
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I have nailed the carriage return portion down.
I am having a very hard time with the multi-threaded asynchronous circular buffer though. I cannot picture in my head how this should work from a mid level perspective.
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You didn't mention any circular buffer before, and neither did I.
Luc Pattyn [My Articles] Nil Volentibus Arduum
Fed up by FireFox memory leaks I switched to Opera and now CP doesn't perform its paste magic, so links will not be offered. Sorry.
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Ok, then scrap that, I thought that was where you were pointing me to, something like a stack. I'm glad it was not, because those looked very complicated!
In trying to write this down and conceptualize it first, I'm wondering if this is a good start?
uC -->
pc thread1 that does a serialport.readLine() into a string, then locks a global array1, copies into it, unlocks global array1 and then clears the string -->
pc thread2 that monitors global array1, locks it, copies data to local string or strings, clears and then unlocks global array1, parses data, adds unique single item delimiter and locks then copies to global array2, unlocks global array2, clears local string or strings -->
pc thread3 that monitors global array2, locks it, copies data to local string, clears global array2, unlocks global array2 and updates pc rich text boxes, then clears local strings
I believe asynchronous data transfer can be achieved if I use some do while loops, to wait for the locks/unlocks.
What do you think?
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way too complex.
Luc Pattyn [My Articles] Nil Volentibus Arduum
Fed up by FireFox memory leaks I switched to Opera and now CP doesn't perform its paste magic, so links will not be offered. Sorry.
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Ok, then don't look at the code I posted a few hours ago 
I'm trying to get it to work, but will try and simplify it also, if I can get it to work. I tried to google for some psuedocode, but didn't find anything.
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Well Luc,
After 2 straight days, I've got it working and working fairly decent. If you want I will post the code, but I'm confident it is still to complex. This is my first attempt at data sharing amongst threads.
I'd love to see an efficient/less complex method if you are willing to share. I'd like to learn to do it the right/efficient way. If you're willing to guide me in the right direction, I'm all ears.
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Why would one need all those threads? All they offer is overhead, bug risks, and performance loss.
You should have created one, not three. And please design before you code, not the other way around.
Luc Pattyn [My Articles] Nil Volentibus Arduum
Fed up by FireFox memory leaks I switched to Opera and now CP doesn't perform its paste magic, so links will not be offered. Sorry.
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I chose multiple threads so that the data could be received asynchronously compared to when it was displayed and so no data was lost ... originally I had a single thread. I know you have serial experience, so if you think a single windows thread can handle the 115000 kbps, I will try and condense the 3 threads into 1.
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You never provided info about baud rates, message length, message frequency, throughput.
On a single core, adding threads does not increase throughput; what it can do, using sufficient buffer space, is cope better with peak loads (it is the buffers who deal with the peaks, the threads are just an easy way to decouple the producer and consumer code).
On a multi-core, adding more threads may or may not help, it depends on a lot of circumstances.
I am guessing your real bottleneck is in the GUI, and then IIRC you are using a TextBox, which is a bad choice for displaying large amounts of line-oriented text. A ListBox is a far better choice, as it does not degrade quadratically under increasing data load. A ListBox holds a list of items, a TextBox concatenates all its data, which gets expensive.
I would use just one thread and a ListBox; some 20 lines of code should do it!
And if I were to need special operations, such as e.g. "save to file", I would add that functionality to the ListBox rather than paying a performance penalty all the time.
Luc Pattyn [My Articles] Nil Volentibus Arduum
Fed up by FireFox memory leaks I switched to Opera and now CP doesn't perform its paste magic, so links will not be offered. Sorry.
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Thanks for the guidance Luc. I will try and condense the code as you've suggested. My code is about 200 lines long for the 3 threads, but it wasn't all in vain as I learned a lot. I was going to use a rich text box so that I could set thresholds and change background colors of each individual box, depending on the value. I would venture that would slow the gui down even more though, so listboxes it is.
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You're welcome.
And you can beautify a ListBox as well, here[^] is an example.
And then, this[^] might interest you.
Luc Pattyn [My Articles] Nil Volentibus Arduum
Fed up by FireFox memory leaks I switched to Opera and now CP doesn't perform its paste magic, so links will not be offered. Sorry.
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Awesome! I will be reading your article. This is great
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