usb device driver development

[muralisridhar]

Posted on September 28, 2009 at 23:48

usb device driver development

[muralisridhar]

Posted on May 17, 2011 at 13:25

hello,

i want to write usb device drivers. my project is a data acquisition system where a pc softwrae is there on host side which contains number keys and some special keys. when ever the user press those keys in pc software i have to recieve the bytes and perform the operation according to it. simulataneously i have to send data periodically to pc software every 100ms and if there is sudden change in the data i need to send that data immediately. here i have to push the data with out host request. The pc software will be most likey written in VB or .net. iam using stm32f103vet6 conroller and writing in embedded c. my doubt is my project belongs which usb device class. can any body help me in this regard. thank you.

[picguy]

Posted on May 17, 2011 at 13:25

>I have to push the data [out via USB] without host request

Sorry, but USB is HOST centric. You can however, REQUEST the host to poll you every few milliseconds. Unless you are doing (more complex) isochronous transfers your poll REQUEST may be delayed. Yet in a fairly quiet system the host polling every 3 milliseconds is generally right on. Every millisecond? Don’t know. First make your device use the HID protocol at the full speed rate of 12 Mbit/s. That’s the basic USB data rate defined by USB 1.1. At least get that to work. Then after you understand what is going on try hi-speed “USB 2.0 rate� (480 Mbit/s) if you need more data speed. It may be that USB can not provide the responsiveness you need. Perhaps your STM32 machine can perform your needed actions faster than the host.

[jj]

Posted on May 17, 2011 at 13:25

@picguy-

Our small group found your post thoughtful and loaded with helpful application data - Bravo!