PORTS Forum

Ports and Interfaces => USB => Topic started by: yalect on February 12, 2014, 04:27:31 am

Title: usb (D+,D-)
Post by: yalect on February 12, 2014, 04:27:31 am

Hi,
Why  usb Pins (D+,D-) is signed (+, -) ?
And At low speed rate each one of them can works like in or out  or one can works both ?
Than you

Title: Re: usb (D+,D-)
Post by: tsybezoff on February 12, 2014, 05:29:40 am

this is differential buses. Its work in an antiphase with the same data, but when have EOF (end-of-frame) buses "meet" with each other.

Title: Re: usb (D+,D-)
Post by: Jan Axelson on February 12, 2014, 10:02:01 am

Yes, low, full, and high speeds all use differential signaling. Differential zero is when D+ is logic low and D- is logic high. Differential one is when D+ is logic high and D- is logic low. Data travels in one direction at a time.

Title: Re: usb (D+,D-)
Post by: yalect on March 19, 2014, 06:59:39 am

thank you Jan Axelson, I understand that each of D+ and D- works like out or in for type of transfer from begining at numeration, will not change after, and which Usually of them is in and other is out ?
thank you