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0 pointsvoxadam8y ago0 comments

What are your bandwidth and latency requirement? More than once I've pondered 6LoWPAN over RS485 using token passing.

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3 comments · 1 top-level

bsder8y ago· 2 in thread

My biggest problem is software stack performance--not physical layer performance. Most protocol stacks in the embedded space other than TCP/IP are mind-blowingly bad.

Being able to obliterate USB, CAN, and RS-232 (to a lesser degree--RS-232 is really reliable but the problem is generally in frequency drift if you don't have a crystal anywhere) in all of my designs and replacing it with ethernet will dramatically improve the reliability of my hardware. The only places I don't currently have ethernet in my designs are where I'm limited to a single pair of wires.

As for RS485, it doesn't really offer me anything that I don't already get with CAN.

IgorPartola8y ago

What do you work on?

bsder8y ago

Lots of industrial stuff related to various types of testing. Performance matters some, but I'm not hard real-time.

However, everything has to work, reliably, in less than ideal environments--mostly high-voltage spikes caused by differences in ground potentials.

USB is a PITA because while data is differential, connection detection is not. So, spikes cause USB disconnects and drivers never cope with that.

CAN is a PITA because it is limited to 8-bytes per message. Good for transducers and 8 bit microcontrollers--not so good for complex control and 32-bit microcontrollers.

Ethernet hits a really great sweet spot of fully-differential and nice single packet size for a 32-bit microcontroller--program like it's 1989, baby.

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