InterviewSolution
Saved Bookmarks
InterviewSolution
| 1. |
Solve : signals USB mouse? |
|
Answer» Hello friends. I searched to the internet how looks signals from usb mouse but I have not found anywhere. Hello friends. I searched to the internet how looks signals from usb mouse but I have not found anywhere.I can't make any sense whatsoever from that sentence. Likewise.The OP wants to know how a USB mouse sends signals information to the Operating system. It is easier explain the older serial mouse with a rubber ball inside of it. For that, the OP would have to search "serial mouse signals' and get some older documents about the mechanical mouse that had a rubber ball. This can explain the serial port. http://en.wikipedia.org/wiki/Serial_port This is about the standard serial mouse . http://www.interfacebus.com/serial-mouse-pinout.html Here is a very recent article with a simple explanation of the computer mouse. Quote by Chris Woodford. Last updated: July 5, 2013.Inside a ball-style computer mouse {I think the OP has a Hawaiian Pidgin dialect.} I want to do this: with a FPGA I CREATE a grafic interface and I want to see the cursor moving on the screen. I'm interested how i could determine the position of the cursor. That link does not help meYou need to clarify what hardware and software you will use. Development software for programmable arrays is very specific to hardware. If you are using a new version of Arduino with VGA, you can find help on other forums. But the Arduino with VGA is a very specific device. It has nits own development environment that runs on a PC. Please clarify what tools you have and what you need.In next image is D + and D- signals from USB. That's what I saw on a logic analyzer. I'm interested how I know what means thows signals [recovering disk space, attachment deleted by admin]Good. So you what to know what that means. First of all, you may need to use a ANALOG o'scope to verify the signals are clean. The logic analyzer does not readily do that. Yje article below is verbose and not really clear. Nut it is a starting point. http://en.wikipedia.org/wiki/USB Here is what you need to know. The USB device has four flat pins taht provide positive and negative voltage and a differential pair. The differential pair is a bi-directional serial link. USB 1.x/2.0 standard pinout Pin Name Cable color Description 1 VBUS Red (or Orange) +5 V 2 D− White (or Gold) Data − 3 D+ Green Data + 4 GND Black (or Blue) Ground The D- and D+ are not two channels . It is one differential channel. The data is one stream. The best way decode the stream to use use a USB hub interface made this purpose. Any attempt to read it as a single end TTL will result is a lot of error. It is not a TTL compatible device. Hope this helps. EDIT: Most users here would have little use for then following. But the OP needs this to understand the issue off single-ended vs. differential pair is interface methods. http://en.wikipedia.org/wiki/Differential_signaling Quote Differential signaling is a method of transmitting information electrically with two complementary signals sent on two paired wires, called a differential pair. Since external interference tend to affect both wires together, and information is sent only by the difference between the wires, the technique improves resistance to electromagnetic noise compared with use of only one wire and an un-paired reference (ground)...Related terms: 'Common Mode Rejection' and 'Ground Loop Noise' Ok. And how I can decodify those signals. Thinking about this: the computer receive those signals and after that, HI can take a decizion (to move coursor on screen or to take a command corresponding for click). How I can decodify that signal to know that the user move the mouse left or right, or he PRESS some button. USB is, of course, a form of serial communication between the conputer and some external device. Serial communication has some mufti-byte protocol for anything more than a simple terminal. Typically there is a n 8-bit serial sequence that bakes a preamble byte which is followed by a data byte. For slow speed devices, 1200 baud is fast enough. But sometimes the baud rate can be very high. Some data analyzers will store a long sequence in HEX or ASCII format to you can examine the data sets and understand the protocol. For a mouse, all moving items would be relative values except for a button push. The button is either on or off. So there would have to be a preamble for each variable item.The data would be relative velocity, not position. Besides the two-byte structure, USB data can be large packets of data. This is more often the case with high speed devices. I have not had need to do this. Years ago I built my own input devices, but now I just get stuff off the shelf and save time. Here is a site for people that really want to know more about USB data packets. http://www.hhdsoftware.com/usb-monitor/screenshots Of course we enjoy having your here, yet I think you will bind more help on one of the hardware hackers sites, LIKE the above link. If that link looks to be too hard, please come back here. The tool they use gets information about the interrupt handler for the USB device. |
|