Comments on: Parts: 1-Wire temperature sensor (DS1822)

By: PICman

PICman — Wed, 12 Jan 2011 15:07:30 +0000

It is temperature control project http://avtomatchik.com/node/56 . The code is written for the PIC12 microcontroller and can be adapted for the PIC16 or others.

By: jc

jc — Mon, 19 Jul 2010 17:53:38 +0000

To all those above concerned about access to multiple devices: it is perfectly possible to connect whatever number of those on the same bus and access them individually without knowing their IDs up front. It uses a very simple and smart detection mechanism. I ordered one and looking forward to it :)

By: acidblue

acidblue — Wed, 07 Jul 2010 02:47:57 +0000

Keep getting: “no device detected 0×02″
What do you guys have R1 connected to?
There is only one 5v wire so I don’t understand why there is two 5+ in the picture.

By: DaveUCSD

DaveUCSD — Sat, 24 Jan 2009 23:16:07 +0000

Awesome work!!

Can anyone help do this in flash??

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1232838392/0#0

By: GCL

GCL — Thu, 01 Jan 2009 16:20:16 +0000

Hello!
As Scotty has noted it will work doing things that we people types do not want to consider.

And from personal experience, using the devices does require knowing each one’s serial number, point of fact, that is what happens when you order a batch, you get completely unique serial numbers, and are expected to know what ones you are using.

In addition the adapter used by the computer host during testing also has one installed to add to the confusing.

By: scott

scott — Sat, 13 Dec 2008 20:34:06 +0000

Anyone interested in these really should check out OWFS (One Wire File System) which is a FUSE based wrapper allowing you to read all (supported) 1-Wire devices as if they were files in linux.

http://www.owfs.org/

By: Scotty

Scotty — Fri, 12 Dec 2008 06:24:19 +0000

There is enough code space in the Arduino, and 4X more in the Sanguino, to incorporate the identify, store, and assign routine needed to introduce new devices in the field. In manufacturing engineering, which I’ve many years experience with, several methods come to mind immediately and the problem is more of which to select for efficiency rather than if it can be done well enough to bother, even with a PIC. As for my single prototype two separate programs were created. One obtains the romid that is then hardcoded into the other program by hand. Debugging additonal code for discovery of just 16 devices would not have been efficient. There is enough space for it though. Oh yes.. I’m running the network in parasitic power mode, hence the need for the 1500 ohms. Powered would do fine with the 4700 ohm.

By: Rectifier

Rectifier — Fri, 12 Dec 2008 02:51:38 +0000

Yep, the one-wire addressing scheme is stupid for real production. I have no idea how it’s actually supposed to be used without reading each device in the factory and hardcoding it. Even if you get them to enumerate themselves, how are you to know which one is where?

However, for a personal project, the ability to chain a ton of them on a 2-wire bus is pretty useful. And the bus pirate will make collecting the rom ids easy (to hardcode into my pic – heh)

scotty, your project is a perfect example of how to use these things. how did you deal with the romid issue? did you hard code it too?

By: Scotty

Scotty — Fri, 12 Dec 2008 00:23:47 +0000

A onewire network running 16 DS18B20 (DS1822 equiv) is monitoring my water lines for freezing and via X10 turning on the heat tapes. Network distance is over 70 feet. Runs on Aruduino and Sanguino. Full CRC checking is in use. One serious note: See Dallas app note 4255 which tells you to use 1500 ohms instead of 4700 for the pullup resistor with these devices because they need 1.5 ma during conversion. Made whole network become totally reliable. Addresses are hardcoded into the software.

By: Chris

Chris — Thu, 11 Dec 2008 21:31:54 +0000

malvolio, I’d suspect that it would not be interesting to duplicate this project on the AVR, if you’ve just developed it for the PIC. Someone else would have to want to do the AVR project for fun.
-Cheers

By: Steve

Steve — Thu, 11 Dec 2008 16:04:02 +0000

I used this sensor with a pic18f4520 to create an automatic water control system. I used this to monitor the temperature of the water, and two stepper motors to adjust the water flow to keep the temperature at whatever the user put in.

By: Malvolio

Malvolio — Thu, 11 Dec 2008 14:36:43 +0000

Any plans to make an AVR version of this for those uninitiated in the world of PIC?!

By: fartface

fartface — Thu, 11 Dec 2008 12:48:29 +0000

What makes these things a giant PITA is that if you install 2 on the line, now you have to know their serial numbers in order to read them. If you are building a simple one off project, this is not a big deal, if you are building something that you intend to manufacture, now things are a world of hurt. you need a bigger processor and nvram so that upon power up it can read all 1wire serial numbers and ask you, “is this #1? is this #2?” and so on.

A single device you can use the generic read function. so in a 16 pin pic, you want to read 5 sensors? design it with 5 1wire busses and put 1 device per bus on it.

1wire parts are very cool but as soon as you scale up past 1 part they become a major PITA when dealing with tiny pic processors.

By: Rectifier

Rectifier — Thu, 11 Dec 2008 07:13:45 +0000

Hey, neat stuff. You guys have definately gone over the top for this thing, by saving the ROM ids and letting users handle them by macro! Above and beyond the call of duty.

Now I’ve got to build me a bus pirate. You guys should sell a kit (or at least PCB) for sure – you deserve to get paid for developing this!

By: Imroy

Imroy — Thu, 11 Dec 2008 03:16:17 +0000

These sensors are great and there’s lots of software for using them. Even better, Dallas/Maxim will send out “samples” for free – two each of up to four parts. Then all you need to do is wire them up. Don’t forget the USB adaptor (DS9490R).