erik malund wrote:
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One note about the most common mistake in implementing RS-485 with the '51 is not taking into account that you must wait 1/2 bit time before turning the bus around due to the fact that TI and RI happens in the middle of the stop bit. I routinely wait 7/10 bit time to account for nominal timing errors.

Erik

Although I doubt this would affect an implementation of RS-485 it might be worth pointing out that TI goes TRUE at the beginning of the stop bit (in mode 1) rather than half way through.

While we're at it, RI goes TRUE slightly after the halfway point in the stop bit due to the bit being sampled three times - something like 9/16ths of the way through.

Whilst TI being flagged so early is useful to get the maximum throughput it really is a nuisance for some applications.