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Originally Posted by Daniel_LaFleur
RJ45 is a loose fit connector and is a standard failure point during shock and vibe testing (bounce causes the contacts to come apart). I don't really like it for the radio connection, but we have little choice here.
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Yes, bounce causes the RJ-45 contacts to come apart, for tiny fractions of a second. But they're small, cheap, and easy to replace on a platform that has minimal life-safety concerns. Besides, the DS protocol uses UDP. Brief periods of unreliability are already a factor!
This is the opportunity for us as mentors to teach our students how to design around these concerns. How can they mount the radio to avoid undue strain on the connectors? How can they strain-relief the cable ends? What else could go wrong to moot those measures, and can those be addressed some other way? They'll never be perfect, but we
can make these connectors very reliable.
You see, we had an off-season exhibition yesterday at the Del Mar Fair. The dual-lock-like mounting tabs on the radio were worn, it fell out, and we lost radio power mid-match. That's a lesson to remember next year.
Quote:
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I'd prefer a connector like the Cannon / Amphenol MS3112E12-10P connector.
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Kids, if you were wondering how to spot someone who's worked on aircraft, that's it right there.
If you
search Mouser for that, you'll find that the *stocked* variant is a $15 part, let alone the special-order spec'ed one, with a lead time that makes AndyMark look like Amazon
Anyhow, what we can't address in our shops is the boot time of the radio. 60-90 seconds in a 2-minute match is flat unacceptable, and it's something that must be addressed by OpenMesh and FIRST. Strip out what isn't needed, and tighten up initialization. (I have a Raspberry Pi Zero booting to console with USB ethernet attached, which boots in 3 seconds. This is attainable.)
I had hoped that FIRST would publish its firmware source for the OMAPs, (thus interested mentors could investigate such things) but Uncle Charlie has probably squashed that.