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  • Oracle Database 11g Upgrade Webcast with Roy Swonger now On Demand

    - by margaret hamburger
    Don't worry if you missed our LIVE webcast  ' Three Compelling Reasons to Upgrade to Oracle Database 11g ' with Database Upgrade expert Roy Swonger.  You can now register for the On-Demand version to learn about Oracle Database 11g upgrade best practices with real customer examples. You'll get access to loads of great upgrade resources for making database upgrades faster and easier. You can also download a copy of our webcast presentation, so register now.

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  • Questions and Answers from Today's Upgrade Webcast with Roy Swonger

    - by margaret hamburger
    Thanks for attending today's live webcast, 3 Compelling Reasons to Upgrade to Oracle Database 11g with Oracle Database Upgrade Expert Roy Swonger. We had an amazing turnout this morning and responded to more than 40 of your upgrade questions that I just couldn't wait to share with you. Don't worry if you missed today's live webcast. You can register for the On-Demand version to learn about Oracle Database 11g upgrade best practices with real customer examples, plus loads of great upgrade resources for making database upgrades faster and easier. You can also download a copy of our webcast presentation.

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  • Is That REST API Really RPC? Roy Fielding Seems to Think So.

    - by Rich Apodaca
    A large amount of what I thought I knew about REST is apparently wrong - and I'm not alone. This question has a long lead-in, but it seems to be necessary because the information is a bit scattered. The actual question comes at the end if you're already familiar with this topic. From the first paragraph of Roy Fielding's REST APIs must be hypertext-driven, it's pretty clear he believes his work is being widely misinterpreted: I am getting frustrated by the number of people calling any HTTP-based interface a REST API. Today’s example is the SocialSite REST API. That is RPC. It screams RPC. There is so much coupling on display that it should be given an X rating. Fielding goes on to list several attributes of a REST API. Some of them seem to go against both common practice and common advice on SO and other forums. For example: A REST API should be entered with no prior knowledge beyond the initial URI (bookmark) and set of standardized media types that are appropriate for the intended audience (i.e., expected to be understood by any client that might use the API). ... A REST API must not define fixed resource names or hierarchies (an obvious coupling of client and server). ... A REST API should spend almost all of its descriptive effort in defining the media type(s) used for representing resources and driving application state, or in defining extended relation names and/or hypertext-enabled mark-up for existing standard media types. ... The idea of "hypertext" plays a central role - much more so than URI structure or what HTTP verbs mean. "Hypertext" is defined in one of the comments: When I [Fielding] say hypertext, I mean the simultaneous presentation of information and controls such that the information becomes the affordance through which the user (or automaton) obtains choices and selects actions. Hypermedia is just an expansion on what text means to include temporal anchors within a media stream; most researchers have dropped the distinction. Hypertext does not need to be HTML on a browser. Machines can follow links when they understand the data format and relationship types. I'm guessing at this point, but the first two points above seem to suggest that API documentation for a Foo resource that looks like the following leads to tight coupling between client and server and has no place in a RESTful system. GET /foos/{id} # read a Foo POST /foos/{id} # create a Foo PUT /foos/{id} # update a Foo Instead, an agent should be forced to discover the URIs for all Foos by, for example, issuing a GET request against /foos. (Those URIs may turn out to follow the pattern above, but that's beside the point.) The response uses a media type that is capable of conveying how to access each item and what can be done with it, giving rise to the third point above. For this reason, API documentation should focus on explaining how to interpret the hypertext contained in the response. Furthermore, every time a URI to a Foo resource is requested, the response contains all of the information needed for an agent to discover how to proceed by, for example, accessing associated and parent resources through their URIs, or by taking action after the creation/deletion of a resource. The key to the entire system is that the response consists of hypertext contained in a media type that itself conveys to the agent options for proceeding. It's not unlike the way a browser works for humans. But this is just my best guess at this particular moment. Fielding posted a follow-up in which he responded to criticism that his discussion was too abstract, lacking in examples, and jargon-rich: Others will try to decipher what I have written in ways that are more direct or applicable to some practical concern of today. I probably won’t, because I am too busy grappling with the next topic, preparing for a conference, writing another standard, traveling to some distant place, or just doing the little things that let me feel I have I earned my paycheck. So, two simple questions for the REST experts out there with a practical mindset: how do you interpret what Fielding is saying and how do you put it into practice when documenting/implementing REST APIs? Edit: this question is an example of how hard it can be to learn something if you don't have a name for what you're talking about. The name in this case is "Hypermedia as the Engine of Application State" (HATEOAS).

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  • What do the ddx and ddy values do in this AABB ray intersect algorithm?

    - by Paz
    Does anyone know what the ddx and ddy values do in the AABB ray intersect algorithm? Taken from the following site http://www.blitzbasic.com/codearcs/codearcs.php?code=1029 (show below). Local txmin#,txmax#,tymin#,tymax# // rox, rdx are the ray origin on the x axis, and ray delta on the x axis ... y-axis is roy and rdy Local ddx# =1.0/(rox-rdx) Local ddy# =1.0/(roy-rdy) If ddx >= 0 txmin = (bminx - rox) * ddx txmax = (bmaxx - rox) * ddx Else txmin = (bmaxx - rox) * ddx txmax = (bminx - rox) * ddx EndIf If ddy >= 0 tymin = (bminy - roy) * ddy tymax = (bmaxy - roy) * ddy Else tymin = (bmaxy - roy) * ddy tymax = (bminy - roy) * ddy EndIf If ( (txmin > tymax) Or (tymin > txmax) ) Return 0 If (tymin > txmin) txmin = tymin If (tymax < txmax) txmax = tymax Local tzmin#,tzmax# Local ddz# =1.0/(roz-rdz) If ddz >= 0 tzmin = (bminz - roz) * ddz tzmax = (bmaxz - roz) * ddz Else tzmin = (bmaxz - roz) * ddz tzmax = (bminz - roz) * ddz EndIf If (txmin > tzmax) Or (tzmin > txmax) Return 0 Return 1

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  • Upcoming Upgrade Workshops in the US

    - by Mike Dietrich
    As Roy is really busy in traveling the whole North American continent I would like to highlight a few of Roy's upcoming workshops with registration links - so simply "click" and register :-) March 23, 2011: Philadelphia, PA March 24, 2011: Reston, VA April 07, 2011: Dallas, TX April 13, 2011: Birmingham, AL April 14, 2011: Minneapolis, MN Roy is looking forward to meet you in one of the above or the upcoming events in California and Oregon. Mike

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  • Thank you for your support throughout 2010!!!

    - by Mike Dietrich
    Now as the calendar year 2010 is close to its end, it's time for a quick wrap-up. The TV stations have shown all their flashbacks already in early December but we'll wait until end of the year ;-) I will post some pictures done by Roy or my throughout our travel in the next days. We've visited a lot of countries - and did more than 60 full-day Upgrade Workshops in 28 different countries: . But the most important thing: We'd like to say THANK YOU to all the wonderful people who'd attend to one of our upgrade workshops in Europe, Asia, Africa or Northern America. It was really great and a big pleasure for Roy and me to meet with you, get a lot of useful feedback, insight views into your environments, plenty of good contacts, recommendations for the slides - and finally some cheers and claps :-) Thanks for all your support, have a great holiday season with your families and your friends wherever you are - and we hope to see you soon again!!! Roy and Mike

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  • WPF : how can i use a picture while i'm showing it?

    - by Roy Gavrielov
    hello, i'm trying to do so but the program throws this exception : An unhandled exception of type 'System.IO.IOException' occurred in mscorlib.dll Additional information: The process cannot access the file 'C:\Users\Roy\documents\visual studio 2010\Projects\Assignment3\Assignment3\bin\Debug\Images\Chrysanthemum.jpg' because it is being used by another process. is there a way to use it while it's open? code : if (imgAddMessage.Source != null) { BitmapImage src = (BitmapImage)imgAddMessage.Source; if (!Directory.Exists("Images")) { Directory.CreateDirectory("Images"); } FileStream stream = new FileStream("Images/" + imageName, FileMode.Create, FileAccess.ReadWrite); JpegBitmapEncoder encoder = new JpegBitmapEncoder(); encoder.Frames.Add(BitmapFrame.Create(src)); encoder.Save(stream); stream.Close(); } thanks.

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  • How to make xxx.one.com load content from yyy.two.com

    - by Roy Peleg
    Hello, I'm currently in need to have xxx.one.com load the content of yyy.two.com. That means that when someone will enter xxx.one.com they'll actually see the content of yyy.two.com (URL in the browser won't change and will remain xxx.one.com). The domains are hosted on separate hosting company. yyy.two.com is on a cPanel and xxx.one.com is on an unknown hosting plan, though I can get its details. yyy.two.com have the same IP of www.two.com and this cannot be changed (as the hosting company told me). Any ideas on how do I tackle this issue? Thanks, Roy

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  • Can I get my video card to output a DVI and VGA signal at the same time?

    - by Roy Pardee
    Hey All, I've got: a lovely 24" monitor, w/both DVI and VGA inputs, a personal desktop w/a Radeon HD Pro 2400 video card (both DVI and VGA outputs) a work laptop w/both outputs, and a KVM switch that handles VGA only Right now I've got laptop connected to the monitor's VGA, and the desktop connected to the DVI. This works, but requires me to switch the KVM and monitor input sources separately, which annoys me (I switch back & forth a lot to make skype calls & manage my music). I'd like to feed both VGA and DVI signals out of my desktop so I can do quick things on my desktop & switch right back, but then when I'm done working, switch the monitor over to DVI to get the crisper picture. Alas, just attaching both VGA and DVI cables to my desktop's video card did not do the trick. Can this card be persuaded to output both signals at the same time? Many thanks! -Roy

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  • background copy large files to a laptop?

    - by Roy Pardee
    Hey All, I like to watch windows media center recorded TV files on my laptop in bed. I find thought that when the programs are in HD I have a lot of stuttering and delays--no doubt b/c of the amount of data being transferred. I actually have a fair amount of space on the laptop's hdd, and wouldn't mind moving the files onto that hard drive, where no doubt my problem would go away. But that requires some planning & time for the files to move. Is there a utility out there that would kind of 'trickle' the files over to the laptop over a long period of time, w/out soaking its bandwidth? Something like ms' BITS tech? Both machines are running win7. Many thanks! -Roy

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  • Delphi, how to make independent windows

    - by Roy M Klever
    I have an application that uses tabs like the Chrome browser. Now I want to be able to open more forms and not be limited to only one form. These forms should act the same but if I close main form all forms are closed. How can I make all forms be equal, so no matter which form I close it only closes that form and not exit application before all forms are closed? Any ideas? Kind Regards Roy M Klever

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  • Upgrade Workshop in Melbourne - Recap

    - by Mike Dietrich
    Thanks to everybody who did attend at our Upgrade and Migration Workshop in Melbourne last Friday. First of all it was a Friday so we really appreciated your patience of staying until the very end And then, yes we know, it was a full room. And we'd really like to thank you It was a great day for Roy and me. And you were such a great crowd with many questions and excellent discussions during the breaks. Please have all successful upgrade and migrations. And feel free to get in touch directly with Roy and me if you have additional questions or if you'd like to become a reference. Please feel free to download the slides from the Slides Download section to your right - or simply use that link here. Ah, and sorry that neither Mark Webber nor Sebastian Vettel did win ... next time -Mike

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  • Upgrade Workshop in Wellington - Recap

    - by Mike Dietrich
    Wow! Wellington is really a wonderful city - except for the weather situation But it was the first time that Roy and me did arrive to a workshop with a ferry boat. We flew in on Friday to Christchurch (btw, this was the longest customs and border control I've ever went through - and I traveled to Israel by Bus via Allenby Bridge from the West Bank some years ago - it took us two hours to go through immigration and customs in the night from Friday to Saturday) and drove up the Southern Island. Very nice Great landscapes, great wines and great people! I'f you'd like to download the slides please download them from the Slides Download section to your right. And next time you'll have to ask more questions Don't be this shy - Roy and me (usually) don't bite -Mike

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  • Workshop in Denver canceled - thanks to hurricane Isaac

    - by Mike Dietrich
    Yesterday Roy did start his journey on time to travel to Denver, CO for today's Upgrade and Migration Workshop.  But unfortunately due to the remnants of  hurricane Issac moving up the East Coast and scrambling up flight schedules Roy's flight from NYC to Denver got canceled after a 3 hour delay leaving Manchester, NH, and there was no option to arrive in Denver this morning on time. So we apologize for canceling that workshop. The local marketing department will contact you regarding an alternative date. Sorry for any inconvenience!

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  • Is it OK to have multiple asserts in a single unit test?

    - by Restuta
    I think that there are some cases when multiple assertions are needed (e.g. Guard Assertion), but in general I try to avoid this. What is your opinion? Please provide a real word examples when multiple asserts are really needed. Thanks! Edit In the comment to this great post Roy Osherove pointed to the OAPT project that is designed to run each assert in a single test. This is written on projects home page: Proper unit tests should fail for exactly one reason, that’s why you should be using one assert per unit test. And also Roy wrote in comments: My guideline is usually that you test one logical CONCEPT per test. you can have multiple asserts on the same object. they will usually be the same concept being tested.

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  • Wix, Launch application after installation complete, with UAC turned on.

    - by Christopher Roy
    Good day. I've been building an installer for our product using the WIX(Windows Installer XML) technology. The expected behavior is that the product is launched, if the check box is checked after installation. This has been working for some time now, but we found out recently that UAC of Win 7, and Vista is stopping the application from launching. I've done some research and it has been suggested to me that I should add the attributes Execute='deferred' and Impersonate='no'. Which I did, but then found out that to execute deferred, the CustomAction has to be performed, between the InstallInitialize, and IntallFinalize phases; which is not what I need. I need the product to launch AFTER install finalize, IF the launch checkbox is checked. Is there any other way to elevate permissions? Any and all answers, suggestions, or resonings will be appreciated. Cheers, Christopher Roy.

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  • Why doesn't WebBBS work now that I've migrated to a new server?

    - by Roy Peleg
    Hello, I've moved a WebBBS board from one server to another. Ever since the board doesn't work. I'm getting an Apache error whenever I try to access the board. Don't even know where to start the debugging, I'm not a Perl person. The file paths remained the same and there isn't any DB involved. http://gammonline.com/members/board/ Any ideas? After a bit of testing I believe that the problem has something to do with the index.cgi which is located in that folder (not getting the error when renaming it). Thanks, Roy.

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  • Looping through worksheets in an Excel (xls) file using classic ASP on a win 2008 server

    - by Roy
    Hi, I have just migrated an older ASP solution to a windows 2008 server and everything works out fine except for using ADOX.Catalog to list all the worksheets in an uploaded xls file. I use the following code: <% Set objExcelCon = Server.CreateObject("ADODB.Connection") With objExcelCon .Provider = "Microsoft.ACE.OLEDB.12.0" .ConnectionString = "Data Source=" & strFilePath & "\" & strFileName & ";Extended Properties=Excel 12.0;" .Open End With Set objAdo = Server.CreateObject("ADOX.Catalog") ' Set ADOX activeConnection objAdo.activeConnection = objExcelCon ' Loop through tables (worksheets) For i = 0 To objAdo.Tables.Count - 1 response.Write objAdo.Tables(i).Name Next Set objExcelCon = Nothing Set objAdo = Nothing % When I run this i get no error message or anything. Anyone got any idea whats causing this? Best regards, Roy

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  • In need of a semantic thesaurus as a SAS

    - by Roy Peleg
    Hello, I'm currently building a web application. In one of it's key processes the application need to match short phrases to other similar ones available in the DB. The application needs to be able to match the phrase: Looking for a second hand car in good shape To other phrases which basically have the same meaning but use different wording, such as: 2nd hand car in great condition needed or searching for a used car in optimal quality The phrases are length limited (say 250 chars), user generated & unstructured. I'm in need of a service / company / some solution which can help / do these connections for me. Can anyone give any ideas? Thanks, Roy

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  • In need of a SaaS solution for semantic thesaurus matching

    - by Roy Peleg
    Hello, I'm currently building a web application. In one of it's key processes the application need to match short phrases to other similar ones available in the DB. The application needs to be able to match the phrase: Looking for a second hand car in good shape To other phrases which basically have the same meaning but use different wording, such as: 2nd hand car in great condition needed or searching for a used car in optimal quality The phrases are length limited (say 250 chars), user generated & unstructured. I'm in need of a service / company / some solution which can help / do these connections for me. Can anyone give any ideas? Thanks, Roy

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  • Samba share not accessible from Win 7 - tried advice on superuser

    - by Roy Grubb
    I have an old Red Hat Linux box that I use, amongst other things, to run Samba. My Vista and remaining Win XP PC can access the p/w-protected Samba shares. I just set up a new Windows 7 64-bit Pro PC. Attempts to access the Samba shares by clicking on the Linux box's icon in 'Network' from this machine gave a Logon failure: unknown user name or bad password. message when I gave the correct credentials. So I followed the suggestions in Windows 7, connecting to Samba shares (also checked here but found LmCompatibilityLevel was already 1). This got me a little further. If click on the Linux box's icon in 'Network' from this machine I now see icons for the shared directories. But when I click on one of these, I get \\LX\share is not accessible. You might not have permission... etc. I tried making the Win 7 password the same as my Samba p/w (the user name was already the same). Same result. The Linux box does part of what I need for ecommerce - the in-house part, it's not accessible to the Internet. As my Linux Fu is weak, I have to avoid changes to the Linux box, so I'm hoping someone can tell me what to do to Win 7 to make it behave like XP and Vista when accessing this share. Help please!? Thanks Thanks for replying @Randolph. I had set 'Network security: LAN Manager authentication level' to Send LM & NTLM - use NTLMv2 session security if negotiated based on the advice in Windows 7, connecting to Samba shares and had restarted the machine, but that didn't work for me. I'll try playing with other Network security values. I have now tried the following: Network security: Allow Local System to use computer identity for NTLM: changed from Not Defined to "Enabled". Restarted machine Still says "\LX\share is not accessible. You might not have permission..." etc. Network security: Restrict NTLM: Add remote server exceptions for NTLM Authentication (added LX) Restarted machine Still says "\LX\share is not accessible. You might not have permission..." etc. I can't see any other Network security settings that might affect this. Any other ideas please? Thanks Roy

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  • Sorting shell items like windows explorer

    - by Roy M Klever
    Hi, I am making a bread crumb bar in Delphi and having some problems regarding sorting the dropdown of the bread crumbs. Strangely enough, even Vista is not consequent when showing these items. I have tried many ways to figure out what is system folders, what is zip files and what is normal folders. It seems like an easy task but so far I have not found any good way of doing it. One way is to use TypeDisplayName from TSHFileinfo but these are localized names so I can not be sure they will be in correct order in every language. Here is the code I use to fill the menu: bool:= IsDesktop(SelectedPIDL); if bool then OleCheck(SHGetDesktopFolder(CurFolder)) else OleCheck(DesktopShellFolder.BindToObject(SelectedPIDL, nil, IID_IShellFolder, Pointer(CurFolder))); if CurFolder.EnumObjects(0, SHCONTF_FOLDERS, EnumIDList) = NOERROR then begin while EnumIDList.Next(1, CurPidl, Fetched) = S_OK do begin FName:= GetDisplayName(CurFolder, CurPidl, SHGDN_NORMAL); Text:= GetPIDLNameForAddressBar(CurFolder, CurPidl); if bool then Text:= PSpecialFolderItem(SpecialFolders[0]).Name + '\' + Text; if Text[Length(Text)] <> '\' then Text:= Text + '\'; NewPidl:= ConcatPIDLs(SelectedPIDL, CurPidl); SHGetFileInfo(PChar(NewPidl), 0, SFI, SizeOf(SFI), SHGFI_ATTRIBUTES or SHGFI_PIDL or SHGFI_SYSICONINDEX or SHGFI_TYPENAME); n:= SFI.dwAttributes; MenuList.Add(GetAttr(n) + FName); AddMenuItem(Text, FName, SFI.iIcon); CoTaskMemFree(CurPidl); CoTaskMemFree(NewPidl); end; end; CoTaskMemFree(SelectedPIDL); Any solution for how to get the correct sorting order? It is strange there is no way in dwAttributes of TSHFileInfo to tell if a folder is a system folder. Roy M Klever

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  • Delphi Shell IExtractIcon usage and result

    - by Roy M Klever
    What I do: Try to extract thumbnail using IExtractImage if that fail I try to extract icons using IExtractIcon, to get maximum iconsize, but IExtractIcon gives strange results. Problem is I tried to use a methode that extracts icons from an imagelist but if there is no large icon (256x256) it will render the smaller icon at the topleft position of the icon and that does not look good. That is why I am trying to use the IExtractIcon instead. But icons that show up as 256x256 icons in my imagelist extraction methode reports icon sizes as 33 large and 16 small. So how do I check if a large (256x256) icon exists? If you need more info I can provide som sample code. if PThumb.Image = nil then begin OleCheck(ShellFolder.ParseDisplayName(0, nil, StringToOleStr(PThumb.Name), Eaten, PIDL, Atribute)); ShellFolder.GetUIObjectOf(0, 1, PIDL, IExtractIcon, nil, XtractIcon); CoTaskMemFree(PIDL); bool:= False; if Assigned(XtractIcon) then begin GetLocationRes := XtractIcon.GetIconLocation(GIL_FORSHELL, @Buf, sizeof(Buf), IIdx, IFlags); if (GetLocationRes = NOERROR) or (GetLocationRes = E_PENDING) then begin Bmp := TBitmap.Create; try OleCheck(XtractIcon.Extract(@Buf, IIdx, LIcon, SIcon, 32 + (16 shl 16))); Done:= False; Roy M Klever

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  • Displaying an image on a LED matrix with a Netduino

    - by Bertrand Le Roy
    In the previous post, we’ve been flipping bits manually on three ports of the Netduino to simulate the data, clock and latch pins that a shift register expected. We did all that in order to control one line of a LED matrix and create a simple Knight Rider effect. It was rightly pointed out in the comments that the Netduino has built-in knowledge of the sort of serial protocol that this shift register understands through a feature called SPI. That will of course make our code a whole lot simpler, but it will also make it a whole lot faster: writing to the Netduino ports is actually not that fast, whereas SPI is very, very fast. Unfortunately, the Netduino documentation for SPI is severely lacking. Instead, we’ve been reliably using the documentation for the Fez, another .NET microcontroller. To send data through SPI, we’ll just need  to move a few wires around and update the code. SPI uses pin D11 for writing, pin D12 for reading (which we won’t do) and pin D13 for the clock. The latch pin is a parameter that can be set by the user. This is very close to the wiring we had before (data on D11, clock on D12 and latch on D13). We just have to move the latch from D13 to D10, and the clock from D12 to D13. The code that controls the shift register has slimmed down considerably with that change. Here is the new version, which I invite you to compare with what we had before: public class ShiftRegister74HC595 { protected SPI Spi; public ShiftRegister74HC595(Cpu.Pin latchPin) : this(latchPin, SPI.SPI_module.SPI1) { } public ShiftRegister74HC595(Cpu.Pin latchPin, SPI.SPI_module spiModule) { var spiConfig = new SPI.Configuration( SPI_mod: spiModule, ChipSelect_Port: latchPin, ChipSelect_ActiveState: false, ChipSelect_SetupTime: 0, ChipSelect_HoldTime: 0, Clock_IdleState: false, Clock_Edge: true, Clock_RateKHz: 1000 ); Spi = new SPI(spiConfig); } public void Write(byte buffer) { Spi.Write(new[] {buffer}); } } All we have to do here is configure SPI. The write method couldn’t be any simpler. Everything is now handled in hardware by the Netduino. We set the frequency to 1MHz, which is largely sufficient for what we’ll be doing, but it could potentially go much higher. The shift register addresses the columns of the matrix. The rows are directly wired to ports D0 to D7 of the Netduino. The code writes to only one of those eight lines at a time, which will make it fast enough. The way an image is displayed is that we light the lines one after the other so fast that persistence of vision will give the illusion of a stable image: foreach (var bitmap in matrix.MatrixBitmap) { matrix.OnRow(row, bitmap, true); matrix.OnRow(row, bitmap, false); row++; } Now there is a twist here: we need to run this code as fast as possible in order to display the image with as little flicker as possible, but we’ll eventually have other things to do. In other words, we need the code driving the display to run in the background, except when we want to change what’s being displayed. Fortunately, the .NET Micro Framework supports multithreading. In our implementation, we’ve added an Initialize method that spins a new thread that is tied to the specific instance of the matrix it’s being called on. public LedMatrix Initialize() { DisplayThread = new Thread(() => DoDisplay(this)); DisplayThread.Start(); return this; } I quite like this way to spin a thread. As you may know, there is another, built-in way to contextualize a thread by passing an object into the Start method. For the method to work, the thread must have been constructed with a ParameterizedThreadStart delegate, which takes one parameter of type object. I like to use object as little as possible, so instead I’m constructing a closure with a Lambda, currying it with the current instance. This way, everything remains strongly-typed and there’s no casting to do. Note that this method would extend perfectly to several parameters. Of note as well is the return value of Initialize, a common technique to add some fluency to the API and enabling the matrix to be instantiated and initialized in a single line: using (var matrix = new LedMS88SR74HC595().Initialize()) The “using” in the previous line is because we have implemented IDisposable so that the matrix kills the thread and clears the display when the user code is done with it: public void Dispose() { Clear(); DisplayThread.Abort(); } Thanks to the multi-threaded version of the matrix driver class, we can treat the display as a simple bitmap with a very synchronous programming model: matrix.Set(someimage); while (button.Read()) { Thread.Sleep(10); } Here, the call into Set returns immediately and from the moment the bitmap is set, the background display thread will constantly continue refreshing no matter what happens in the main thread. That enables us to wait or read a button’s port on the main thread knowing that the current image will continue displaying unperturbed and without requiring manual refreshing. We’ve effectively hidden the implementation of the display behind a convenient, synchronous-looking API. Pretty neat, eh? Before I wrap up this post, I want to talk about one small caveat of using SPI rather than driving the shift register directly: when we got to the point where we could actually display images, we noticed that they were a mirror image of what we were sending in. Oh noes! Well, the reason for it is that SPI is sending the bits in a big-endian fashion, in other words backwards. Now sure you could fix that in software by writing some bit-level code to reverse the bits we’re sending in, but there is a far more efficient solution than that. We are doing hardware here, so we can simply reverse the order in which the outputs of the shift register are connected to the columns of the matrix. That’s switching 8 wires around once, as compared to doing bit operations every time we send a line to display. All right, so bringing it all together, here is the code we need to write to display two images in succession, separated by a press on the board’s button: var button = new InputPort(Pins.ONBOARD_SW1, false, Port.ResistorMode.Disabled); using (var matrix = new LedMS88SR74HC595().Initialize()) { // Oh, prototype is so sad! var sad = new byte[] { 0x66, 0x24, 0x00, 0x18, 0x00, 0x3C, 0x42, 0x81 }; DisplayAndWait(sad, matrix, button); // Let's make it smile! var smile = new byte[] { 0x42, 0x18, 0x18, 0x81, 0x7E, 0x3C, 0x18, 0x00 }; DisplayAndWait(smile, matrix, button); } And here is a video of the prototype running: The prototype in action I’ve added an artificial delay between the display of each row of the matrix to clearly show what’s otherwise happening very fast. This way, you can clearly see each of the two images being displayed line by line. Next time, we’ll do no hardware changes, focusing instead on building a nice programming model for the matrix, with sprites, text and hardware scrolling. Fun stuff. By the way, can any of my reader guess where we’re going with all that? The code for this prototype can be downloaded here: http://weblogs.asp.net/blogs/bleroy/Samples/NetduinoLedMatrixDriver.zip

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