That's right, this post is about that Universal Serial Bus (USB) that you probably use every single day and probably never gave a second thought as to how it works.
There are several types of USB connectors that have various uses:
The most common types you have probably encountered are the Type A and mini USB connectors. The difference between the Type A and Type B is Type A is typically for a host, that is, the device that is sending out the information, and Type B is for the device that is receiving the information. Nowadays, a lot of deices that use USB can both receive and transmit data so Type A is the most common.
If you ever look at a USB plug closely you will most likely see 4 or 5 connectors. Typically the two outside pins are used to supply the Voltage as well as the Ground. So when you connect your phone into the wall to charge it, it is only really using the two outside pins, and the two in the middle aren't being used at all.
This is the part that I found most shocking, there are only two pins used to transmit the data, the two middle pins and these two pins send the same exact data, just one is the negative of the other. This is called a differential pair and I am not going to go into the specifics of why they do this, other than that is to ensure that the the signal received is clean and free of noise. I think the fact that these two little pins can transfer over a billion 1's and 0's in a few seconds is amazing, and I know if someone asked me to design a device to do that I would have to use way more than two pins.
I guess that is just something to think about when you are uploading pictures from you phone to your computer.
Picture 1
http://www.l-com.com/lcom_emails/2008/092308/usb_connectors_sm.jpg
Picture 2
http://newnex.com/images/ura-1001-clear.jpg
