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My latest creation


#1

I mentioned previously that I was waiting to see how my first DorkbotPDX board turned out before I sent and USBizi module boards out for production. I just got the last pieces I needed to put it all together, and here’s the result.

The board is extremely simple, it provides a .1" header, 4P4C connectors (x3), and the one pullup resistor required for a Dallas/Maxim 1Wire bus. All you need to do is connect VDD, GND, and DQ (any FEZ digital pin), and you’re off to the races. Here, I’ve got two DS18B20 temperature sensors attached, but any 1Wire device could be used (parasitic-mode power would require additional components).

It works great!


#2

Close-up of the board


#3

I’ve also got a driver for the DS18B20 sensor, as well as a little class that wraps up GHI’s OneWire class for scanning the bus for devices. I’ll post it on the code site when I clean it up a bit.


#4

Nice! How long is that bigger wire?


#5

The long one is 24 feet long (about 7.3 meters). I’m not sure it’s long enough for my purposes, I may need closer to 9 meters.

I’m currently powering it at 3.3V, but I may need 5V to get it to run that far.


#6

Love the boards. What footprint is the RJ connector - I ask because I have a handful of connectors with nowhere to go, and a bigger handful of DS18B20’s with plenty of ideas where to go but nowhere to plug into.

I’ve never really cracked a good design for the one-wire libs - I always thought it’d be ideal to have the code for the “one-wire network” resilient to removal and additional insertions, as well as things like get-current-reading(device) and get-current-reading(all). I also wanted “soft names” so I maintain a big list of name vs ID and scan that - adding new ones as needed if a new node needs to get added or it’s “name” (location) gets moved. So I’m hanging out to see your code !


#7

At the moment I have a 1-wire network of about 20 mixed sensors (ds18s20, ds18b20, ds2438). I can plug them in and the soft picks them up automagically. The readings get stored in an SQL2008 database, and that where I map sensor ID’s to locations.
I still need to finetune the software side because occasionally i see a temperature of -32500°C in my db table, though there’s no sign outside of an ice-age :wink:


#8

The connectors I used were these:
http://search.digikey.com/us/en/products/A-2004-3-4-LP-N-R/AE10381-ND/2183632

I created the footprint in Eagle, and it worked the first time :slight_smile:

I don’t have any hot-plug functionality built in, but I could certainly implement it with what I’ve got.


#9

Dear Eric:

Could you please tell me where I can find an example for storing sensor data to SQL Server 2008 form my FEZ Domino?

Thanks.


#10

Tzu, the data goes over tcp to an app i wrote, and the app takes care of saving them into the db.


#11

Hi Eric:

Thanks, had you share your code on “Code” about this?


#12

Tzu, my code is not on code share because it is not generic enough, my app is doing also other things besides saving to the db.


#13

Ok,let me try it by myself. If I meet some problems I will come here for help. Thanks.