TRANSMISSION MODES

The transmission of binary data across a link can be accomplished in either parallel or serial mode. In parallel mode, multiple bits are sent with each clock tick. In serial mode, 1 bit is sent with each clock tick.

While there is only one way to send parallel data, there are three sub classes of serial transmission: asynchronous, synchronous, and isochronous.

Topics discussed in this section:

• Parallel Transmission
• Serial Transmission

Data transmission and modes

Parallel transmission

Serial transmission

Note

In asynchronous transmission, we send

1 start bit (0) at the beginning and 1 or

more stop bits (1's) at the end of each

byte. There may be a gap between

each byte.

Note

Asynchronous here means

“asynchronous at the byte level,”

but the bits are still synchronized;

their duration's are the same.

Asynchronous transmission

Note

In synchronous transmission, we send

bits one after another without start or

stop bits or gaps. It is the responsibility

of the receiver to group the bits.

Synchronous transmission