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I have following wire as shown below, one end has male USB connector and other end has four wires. I know, when connected to laptop, the RED one acts as voltage source and BLACK as ground. If I give 2 bits data input to GREEN and YELLOW one, is there any software or API for (Python, C or any other language) to know about state of those two wires ? I mean to check if GREEN or YELLOW one have a voltage or not.
Please guide me if I am asking the wrong question. |
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No, you cannot sense the USB wire state directly. USB is a much more complex interface than that, it is no comparison to the old style serial and parallel ports that could be used for direct I/O with a simple driver program. A complex handshake is exchanged with the PC even before the first byte of 'real' data/payload can sent. Maybe your PC has a parallel port that can be used? Or you should use a USB to GPIO converter which are broadly available for varying prices (both extremely high and extremely low). |
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What is your ultimate goal? If it is to observe the USB protocol, you can use a relatively inexpensive or relatively expensive logic analyzer. If your goal is to capture bytes on your computer, you can get a USB debugger for your operating system (e.g., OS X has a free USB Debug Kit). If your goal is to have an easy way to determine if you put a voltage onto an input, you'd be better off using a USB-->GPIO, as jippie suggested, or you could go down the (more expensive) arduino route and have a lot of room to grow if you wanted to do more stuff with the inputs prior to analysis on the computer. If you really want a super-simple way to get a voltage value into your computer without buying new hardware, jippie's suggestion to use the parallel port is a good one, and you could also investigate using your microphone input as a jerry-built solution. |
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