19 Oct
2011
19 Oct
'11
5:29 p.m.
On 10/19/2011 04:16 PM, Tony Duell wrote:
Err, no. It's very common on long/fast serial lines to have 2 wires
differentially driven -- so that when one is high the other is low and
vice versa. The receiver then looks at the polarity of the differnce in
votlage between these 2 lines. It leads to better noise immunity, for
example.
RS422 is one such interface. Apple Mac serial ports use this for the data
lines.
And v.35, some flavors of SCSI, the drive-side interface in
FibreChannel, SATA, SAS, SSA, twisted-pair forms of Ethernet, PCIe (and
indeed most other high-speed digital signals on PCBs these days), most
copper-based telephony, all the signals in a Cray-1...differential
signaling is everywhere.
-Dave
--
Dave McGuire
New Kensington, PA
So an interface which transfers data bit-serially over
a pair of
differentially-driving lines is a parallel interface? (2 lines are
changing at once)
Sounds like redundancy to me.