query on USB cables

yussyyussy Registered Users Posts: 3 ■□□□□□□□□□
Hi,

I do understand that USB cables have four pins, first & last pins carries (5v) for power and the inside two for data
transfer(Data-, Data+). What I don't understand is why? some USB cables only charge but don't transfer data when each end is connected to the computer and device(smartphone) respectively or some just display only the phone memory without the SDcard memory on the windows explorer.
Sign In or Register to comment.