Framing error and Break char

[oe]

Posted on September 21, 2009 at 08:25

Framing error and Break char

[oe]

Posted on May 17, 2011 at 13:24

I need to be able to separate a break char from a true framing error.

When STM32 recives a break char (byte value = 0), it generates a framing error. In the datastream I recive, there occur ''real frame errors'' that I need to be able to detect and handle. Do anyone have any suggestions??

[st3]

Posted on May 17, 2011 at 13:24

Quote:

I need to be able to separate a break char from a true framing error.

But, surely, a ''Break'' is not a character? A ''Break'' condition is when the line is held in the Spacing state for longer than</i> one complete frame. This does, of course, constitute a framing error...

Quote:

Do anyone have any suggestions??

Separately monitor the line to detect when a true Break occurs?

[ericvanolden9]

Posted on May 17, 2011 at 13:24

To detect a Break you can use combination of framing AND receiving character 00. If character is other than 00, this is a normal framing error.

[st3]

Posted on May 17, 2011 at 13:24

Quote:

To detect a Break you can use combination of framing AND receiving character 00.

But you are still left with the problem to distinguish a framing error on a genuine NUL character (a byte with value 0) from a true BREAK signal... I think the only way to do that is to separately time the BREAK?

[oe]

Posted on May 17, 2011 at 13:24

Tanks for the tip.

I did a EXT interupt that checks if the line is low for more than a fame, to be able to separate a ''break char'' = one frame low, from a framing error = Missing stop bit, or that the line is low for longer period than one frame.