Helpful ReplyHot!USART Interrupt 4 Byte Limit???

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Jerry Messina
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Re: USART Interrupt 4 Byte Limit??? 2018/02/19 16:43:51 (permalink)
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I would imagine you're much more likely to get something like a framing error from a noisy line than an overflow

Probably true, but if you're unlucky enough to have the noise generate a false START then your chance of getting OERR instead of FERR increases.
 
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qɥb
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Re: USART Interrupt 4 Byte Limit??? 2018/02/19 17:19:39 (permalink)
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A false start will just generate a spurious 0xFF character.
Again if interrupts are not disabled for more than a millisecond, it will NOT generate an OERR.
 

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jack@kksound
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Re: USART Interrupt 4 Byte Limit??? 2018/02/20 09:39:29 (permalink)
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qɥb
A false start will just generate a spurious 0xFF character.
Again if interrupts are not disabled for more than a millisecond, it will NOT generate an OERR.
 


I can see how that is now with the receive register and the FIFO buffer that using the interrupt to read the USART will prevent an overrun if you do it fast enough (don't turn off the ints as you say). It is a combination of the baud rate and the depth of the FIFO that determines how long the ints can be disabled before you have a potential overrun issue. I had not really thought about it that much before, I seldom use the USART in situations where I am pushing the limit on receive speed. 
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