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Gadgeteer OneWire module


#1

I previously created a little board with 3 RJ-9 jacks and the pullup resistor required to do a OneWire bus. I created this board because cheap telephone wire is widely available and plenty for quite long distance OneWire sensors.

I’ve decided that it may be useful to have this be Gadgeteer compatible, so I’ve laid this out, and I’m hoping for a bit of feedback.

I believe it would be highly convenient to switch out the RJ-9 jacks (which are four-conductor) for RJ-11 jacks (which are six-conductor) because long telephone wires with RJ-9 plugs aren’t readily available, while RJ-11 versions are everywhere.

Other than that, what do you think?


#2

Great idea. Count me in for a couple boards. RJ11 would give us 2/wire, or maybe even 6/wire in parasitic mode?


#3

You can connect as many as you want, all on the same wire. It’s truly “one” wire (for data). In the RJ-9 connector, one conductor goes unused. In RJ-11, three would go unused.

The RJ-9 connector could, I suppose, support two completely separate busses, and the RJ-11 could support four, but I’m not sure that’s really useful…


#4

RJ11 is almost as available as RJ45, and while it’s overkill (which I love) have you considered this (edit: where “this” means RJ45s :))?

Personally, I love the idea of this kind of board. Did you mean to show the image of the board ? I have thought about making a DS18B20 module that has in/out connectors and a footprint for the DS18B20 and resistor, for scattering around the house in places I want to monitor the temperature. Could your board be “dual purposed” to do something like this, if you did not attach the Gadgeteer socket, and just add the footprint for DS chip?


#5

@ godefroi - one bus, i knew that :-[ With your existing one wire setup do you solder all sensors to a length of wire, or do you do some kind of modular thing with male and female RJ jacks? I remember seeing a picture of it around here somewhere…


#6

Yeah, like I said, I’d do RJ11 instead of RJ9, because cords with RJ9 jacks on them are generally short and curly :slight_smile:

It could definitely be dual-purposed to this, and I’d definitely consider putting a footprint for a DS18B20 on the board. For my own designs, however, I’ve just been soldering the DS18B20 to the CAT3 cable…

I think I’ll have a few made to test the board design, anyone else want one? I wouldn’t be populating it…


#7

I have a crimper and a heap of connectors for RJ11 (4 and 6 connector variants) as well as RJ45s. But I don’t have RJ11 PCB mount sockets. Nor do I have RJ11 PCB mount sockets either, so I guess I will need to find the right ones of those eventually too !


#8

Here it is with a DS18B20 footprint. It could be left unpopulated for those who don’t need it. The board could be used as simply an extension for an existing OneWire bus by populating only an RJ-11 jack and the DS18B20 footprints.

I think I’ll have a set made by DorkbotPDX, they’ll cost me (I figure) about $4.40 per bare board.


#9

Are you up for sharing the eagle files? This will simplify wiring my turtle tank monitoring system nicely! I would like to tweak it and coop the extra wires/pins for another sensor. Maybe a couple MakeBread modules will show up in your mailbox for the effort…

BTW - Laen’s custom purple PCB service rocks!

Thanks!


#10

If you need it faster/cheaper, but not that sweet purple color, consider using Seeed’s Fusion PCB service. I’ve had good luck with them so far.

5cm x 5cm 10 units will run you $10. 5cm x10cm will be about $25 (green)

Pete


#11

Sure, I’d share the files. I can put them on the wiki if you’d like, or I can send them directly to you if you let me know how.


#12

Email = my forum name at gmail. My (well, my wife and son’s) turtles thank you :slight_smile:


#13

Pete, seeed vs Dorkbotpdx can also be highly dependent on how much “wasted” space there is on the seeed “standard” sizes, or how well you can panelise them yourself, as Laen charges based on real square-inch space used. The other thing I have against the higher quantity sources (seeed and itead) is the higher quantity - when doing “real” prototypes or boards that you would never need more than 3 of. I have not used any of these services myself, but for me making 3 boards vs 10 appeals to the treehugger in me. But speed these days is certainly a different story !


#14

@ pete - not to beat a fast horse, but faster (by a week or so) and cheaper (a few dollars) don’t really have any value for me (the hobbyist who is mostly prototyping just a few boards). This little alliteration sums it up:

Pragmatic Purple People Possibly Possess Profound Patience


#15

They’re here!