Klemen Dovrtel wrote: > Hello everybody, > > I am studying EPP data transfers via parallel port and i could not find the > answer to my simple question: Is it possible to transfer several bytes of > data in single base-period? How many bytes can be transferred? > > Umm, you question is not very specific. If you are inquiring about the hal_parport driver, it doesn't use EPP. I use EPP mode in the driver for my parallel port connected devices, and they transfer many bytes, often 20-75 per board, every servo period. I don't see why it couldn't alos be done in the base thread, but if that is running at a fast rate, you have to be very concerned with the complete thread time. With a fast PCI parallel port plug-in card, a complete EPP transfer can be done in as little as about 600 ns, with an on-motherboard ISA-interfaced multi-IO chip, it may take as long as 1.2 us. More than a few transfers might be too slow for your thread.
How many has to be determined by your thread dispatch rate, the speed of the parallel port, and the realtime jitter, to give enough margin so you never overrun the period. Jon ------------------------------------------------------------------------------ Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft MVPs and experts. ON SALE this month only -- learn more at: http://p.sf.net/sfu/learnnow-d2d _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
