Comms giving EMC failure?

[Faringdon]

AYK, comms switching edges give EMC fails...
Why dont people slow down the transmission frequencies as much as possible, and also  use comms protocols where the switching edges are deliberatley damped....by the way, what are those comms protocols wherein the bit edges are damped (slowed up) for EMC reasons?...there must be such a comms protocol?

[exmadscientist]

AYK, it's edge speed that matters most, not frequency....

Most people just limit the edge rate with either a capable driver or small filter and it isn't an issue for speeds up through USB High Speed or so. Protocols don't damp edges, drivers do.

[tggzzz]

Classic treez word salad confusing/conflating several concepts.

There are also many concepts he neglected to include. He should start by reading any decent comms theory book; I quite like Sklar's  https://www.academia.edu/43182727/Digital_Communications_Fundamentals_and_Applications_2nd_Edition_by_Bernard_Sklar

[Faringdon]

Most people just limit the edge rate with either a capable driver or small filter and it isn't an issue for speeds up through USB High Speed or so. Protocols don't damp edges, drivers do.

Thanks, though i thought the driver is always "inside the micro" or whatever, and realistically you have no access to it?

...Or say,  for USB, the driver is in the offtheshelf "USB device", and its not cost effective to make your own driver?...so your stuck with the offtheshelf drivers?

[coppice]

Most people just limit the edge rate with either a capable driver or small filter and it isn't an issue for speeds up through USB High Speed or so. Protocols don't damp edges, drivers do.

Thanks, though i thought the driver is always "inside the micro" or whatever, and realistically you have no access to it?

...Or say,  for USB, the driver is in the offtheshelf "USB device", and its not cost effective to make your own driver?...so your stuck with the offtheshelf drivers?

This is why many MCUs now have selectable drive strength on some of their I/O pins. It can really help with EMI when a signal is attached to a long trace that can't be routed very well.