DIY project cabling options

yarisboy

I've officially started the "new and improved" rev. B of my piggyback board. On the original design, I had a 10-conductor ribbon cable going to the 4x7 segment LED displays (using six-conductors). Now I'm reviewing options for that. I like using cable types we all seem to have in our junk drawers even though the usage is non-standard. I have a lot of RJ-11 cables but none of them carry all six available conductors (RJ-25 6P6C). Second on the scrap list is left over RJ-45 cables. If I use RJ-45 board connectors then I have an interface with the locking tab easily ported through the side of the enclosure. Also if I wished to have data-out feed back from my serial displays the RJ-45 style would have an available wire for that. I've broached this type of discussion before so I have to be thick-skinned enough to hear how dumb this idea is, and why. Thing is, the parts count for such an inclusive multi-function board is getting higher and I'm concerned about the over-all parts total cost. I don't want the cost to go above what wage-earners like me can realistically afford. I've nailed down what type of cabling and connectors I'll use on the other 75% of the I/O.

kwinn

RJ45 cables and connectors are quite common and handy to use for this type of application. Problem is if everything uses the same connectors how does someone know what plugs in where when you have a lot of connections. Not a problem for homebrew one of a kind units, but not a good idea for production equipment.

Toby Seckshund

I agree, Where I work they use CAT5 on RJ45s for all sorts of things. Even with a cable schedule things do get cross plugged and sometimes the results are not good.

Everything is being built around this infra-structure now so I suppose I had better get used to it. Broken things = me having a job (mustn't grumble)

RinksCustoms

RJ-45 comes in two varieties, patch and crossover.. what are the odds of frying a piggyback by mistaking one kind for the other? I have at least one of each kind, they look the same, and neither have labels on them to tell them apart.. i figure the odds are 50/50 of frying a project

perhaps there is a way to route the connections on the jacks so that either cable can be used?

kwinn

I like to use the 2 row pin headers where possible, remove 1 pin, and block the same location on the female cable connector. If a board has multiple cable connectors J1 would have pin 1 removed for polarization, J2 pin 2 removed, etc. I also like to minimize the number of connectors by using one large connector on the main board and splitting the ribbon cable to go to several smaller connectors if multiple connections are required.