8051/serial port lockup

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   we are seeing a problem which we suspect *may* be an intermittent
serial port lockup on the 8051 series.  We have an 8051-based device
which quits communicating sometimes.
   Basically we suspect that another component is holding the serial
port in the low (break) state for prolonged periods of time and are
wondering if anyone knew of any problems with doing this.  We are in
the process of fixing the other component to not behave this way, but
are looking to see if we can gain any confidence that this may
actually fix the problem with the 8051-based device.


Re: 8051/serial port lockup
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You are not providing much information here.
What does the 8051 talk or listen to?
What kind of lockup do you experience?
What or how can "the other component" keep which serial line in break state?
Is the software waiting forever for the RI or the TI to become set?
Is any data present on the serial line (oscilloscope)?
What is the baudrate?
Is the data continuous or packetized?
When continuous, are there gaps in the stream to enable the receiving end to


Re: 8051/serial port lockup
You aren't providing enough informations.
I just wanted to say that I have worked with many different 8051
series microcontrollers and had no problem whatsoever on the
hardware level. And when routines are written correctly there
should be no problems at all.

Anyways you might check errata sheet of your microcontroller to
see if there are any known bugs in microcontroller.

Re: 8051/serial port lockup
On 12 Dec 2003 06:32:08 -0800, the renowned dlindauer@notifier-is.net

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I vaguely recall some relatively simple to work-around issue with
interrupt-driven comms on 8051s, but no details. Try googling for code

Best regards,
Spehro Pefhany
"it's the network..."                          "The Journey is the reward"
snipped-for-privacy@interlog.com             Info for manufacturers: http://www.trexon.com
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Re: 8051/serial port lockup
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  Lockup and async ports is something of a contradiction in terms.

  If you mean 'loosing the odd character', then maybe : A break will
cause a INT, and then it's up to the SW to decide -> [break, not char].
Most newest C51 UARTS have flags that can help with this (FE).
  Check what your SW actually does, with Break's.


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