Hi Mircea,

I don't know if you searched already, but I find some interesting links just
by adding your subject title in a search engine...

Synchronous and Asynchronous Communications
There are two basic types of serial communications, synchronous and
asynchronous. With Synchronous communications, the two devices initially
synchronize themselves to each other, and then continually send characters
to stay in sync. Even when data is not really being sent, a constant flow of
bits allows each device to know where the other is at any given time. That
is, each character that is sent is either actual data or an idle character.
Synchronous communications allows faster data transfer rates than
asynchronous methods, because additional bits to mark the beginning and end
of each data byte are not required. The serial ports on IBM-style PCs are
asynchronous devices and therefore only support asynchronous serial
communications.

Asynchronous means "no synchronization", and thus does not require sending
and receiving idle characters. However, the beginning and end of each byte
of data must be identified by start and stop bits. The start bit indicate
when the data byte is about to begin and the stop bit signals when it ends.
The requirement to send these additional two bits cause asynchronous
communications to be slightly slower than synchronous however it has the
advantage that the processor does not have to deal with the additional idle
characters.

An asynchronous line that is idle is identified with a value of 1, (also
called a mark state). By using this value to indicate that no data is
currently being sent, the devices are able to distinguish between an idle
state and a disconnected line. When a character is about to be transmitted,
a start bit is sent. A start bit has a value of 0, (also called a space
state). Thus, when the line switches from a value of 1 to a value of 0, the
receiver is alerted that a data character is about to come down the line. 

This and more at:
http://www.taltech.com/TALtech_web/resources/intro-sc.html#Synch


Regards,

E.J. Smit



> -----Original Message-----
> From: Mircea Coman [mailto:mircom@;yahoo.com] 
> Sent: woensdag 6 november 2002 14:34
> To: Multiple recipients of list CHIPDIR-L
> Subject: RS232 serial SYNCRONOUS communication
> 
> 
> Hello list members,
> 
> Do you know where I could find documentation regarding
> RS232 serial SYNCRONOUS communication?
> I'm interested in explanation of several clock
> configurations (internal, external) and practical
> diagrams of cables needed to connect two data
> communication equipment in each configuration.
> 
> Thanks,
> Mircea
> 
> 
> 
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> Author: Mircea Coman
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-- 
Author: Elbert Smit
  INET: [EMAIL PROTECTED]

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