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Altera_Forum's avatar
Altera_Forum
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12 years ago

ISR driven UART is missing characters (even at 9600bps... same prob at 230400)

Any ideas on what I'm missing here that is causing me to miss characters? I'm interfacing to a device that shoots out RS232 packets (up to 200 per second if the bps can handle itI can select t...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
12 years ago

OK, did the above... recompiled code... and now every time I run thru the ISR I check the flags and I'm getting this after I try to send a 500byte file via hyperterminal's 'send text file' at 115200bps(n-8-1):

111101000

I decode this to be (right to left)

ROE (receive overrun error)

TMT (Transmit Empty)

TRDY(Transmit Ready)

RRDY(recieve Ready)

E (exception)

So, it appears that the NIOS2 has an IRQ latency of around 2-3ms?