1-wire info and recommendations

[Gina]

To Charlie or anyone else...

Having had the suggestion of using 1-wire for extra sensors from Charlie as an aside to my "spikes" thread, I've been Googling for info and have found a certain amount but lacking in specifics. I would like to set up a 1-wire network and connect it to one of my computers. All have USB and the PCs have serial ports. So either serial or USB would be OK.

Charlie mentioned a specific temperature sensor and I have found a UK supplier but I would like to know how to build (or buy) a 1-wire to PC interface. Maplin have a big selection of PICs at affordable prices but I guess I'd need a programming unit to put the code in it. Maplin supply these too. I'm sure all this is far less complicated than it looks. I'm interested in implementing other sensors too.

Any suggestions/info would be much appreciated.

[captzero]

Hi Gina,

This looks promising. Hobby Boards says: "These products include weather and environmental monitors (lightning detectors, temperature and humidity detectors, soil moisture meters, etc.) and other devices such as motion detectors and counters. These are offered as fully assembled units, as well as individual circuit boards and kits for the electronic hobbyist."

http://www.hobby-boards.com/catalog/main_page.php

[apenwith]

Hi Gina
For a 1-wire usb adapter try Homechip. Ole and I are using the 1-wire for the sunshine recorder.
Regards
Alan

[mcrossley]

I have a standalone temperature logger based on a Dallas 1-wire button sensor that a mate built for me. It has a serial PC interface and is programmable for the capture interval, alarms etc. I think he got the cct off the Dallas website. He also got a batch of the sensors free as 'samples' . (he seems to get most of his 'one-off' components as freebie samples! ). Moral: always check the manufacturers website for the 'samples' link.

Last time he ordered a batch of 10 of the more pricey Atmel processors, the supplier only had 9 in stock, so they shipped them FoC as they could not fulfill the order - some people are just lucky!

[Charlie]

Hi Gina,
I'm just starting to play with these devices so I'm sure you'll get better advice from some of the more experienced folks, but I think you can find everything you need on the primary producer's web site. This used to be Dallas Semiconductor (which most of the documentation still shows) but is now called Maxim (www.maxim-ic.com).

You can certainly implement a "1 wire" master with a PIC microcontroller. (There is one running on the corner of my desk right now), but if playing with micros is not a hobby you really want to pursue, Maxim lists a collection of bridge ICs and even assembled bridges to master a 1 wire bus from USB or RS-232. They also have downloadable software to drive the device. One of the many personal sites on the web stated that Maxim only supplies a Windows version, but this individual was able to get Linux working quite easily.

[steve]

I assume that 1-wire support would be fairly easy to add to Cumulus?

[Gina]

Thanks for your replies and the links - they look useful I've had a quick look and bookmarked them for further study.

[Charlie]

Hi Steve,
To add it to Cumulus would be straight forward if there was a standard piece of hardware to bridge the bus to RS-232 or USB with a standard method to talk over it. Unfortunately, there's no PC card, so I'm not sure what most people are using.
The bus itself is a simple query / response protocol. There is an initial configuration you need to send, then the temperature probe (for example) responds to a query with a 2's complement number that gets multiplied by a constant whose value is based on how many bits resolution were configured. Where it gets tricky for Cumulus, is that many people will have implemented their own flavor of communication between the application layer, and whatever they are using to talk to the 1-wire bus. It could be a driver in the OS, or a microcontroller, or something in between. It might return raw data, or a temperature already calculated, or something else. You might have to carefully control the timing - or not. The trouble with highly flexible systems is that people flex them
Perhaps the simplest way to integrate, would be to define an interface to Cumulus that anyone wishing to build their own kit could use.

[mcrossley]

Charlie, I couldn't agree more. Cumulus shouldn't really have to handle low level 1-wire stuff. In an ideal world it shouldn't have to handle various different PWS protocols either, there should be a standard 'Weather API' that everyone adheres to and provides drivers for. I contribute to such an interface for astronomy systems called ASCOM that abstracts the various telescope/focuser/camera/filterwheel hardware from the applications that use them.

This works very well in the main, and work is even under way on an ASCOM weather interface, albeit of limited scope, as astronomers are primarily just interested in if it is cloudy or has started to rain so they can close the observatory roof!

[gemini06720]

I assume that 1-wire support would be fairly easy to add to Cumulus?

Steve I have not yet gotten myself involved with the 1-Wire technology, but I have read a great deal about it.

Looking at the Hobby Boards site I noticed that they offer two adapters to connect the 1-Wire network to a PC - through either a 1-Wire serial adaptor or a 1-Wire USB adaptor.

The Hobby Boards site has pages on How To use the boards in the 1-Wire network as well as a links page to other software using the 1-Wire technology.

[Gina]

Useful site that I've bought a book on weather stations, sensors and the 1-wire system http://www.amazon.co.uk/gp/product/0470 ... ss_product which uses the HobbyBoard modules modules and kits in their examples. From a quick look through it (only came this morning) it seems to be a useful book OK I dare say all the info is on-line but a book is easier to read.

[steve]

Oooh - I've seen that book before and thought about buying it...

[Gina]

I think it's good value for a book. 450 pages. Covers general info about how weather is/was measured, shows a couple of weather stations including the Davis Vantage Pro 2 and goes on to talk about 1-wire principles, circuits and systems and the software to run them. It looks like 1-wire should be cheap and reasonably easy to implement. The latter will be a case of "the proof of the pudding is in the eating"

I have ordered a couple of things from HomeChip. Their prices seem very reasonable and ordering from their UK site avoids any problems with international delivery. I've ordered their low cost serial to 1-wire adaptor, some DS18B20 1-wire temperature sensors and a DS2450S+ 1-wire quad A/D converter. That should do to get me going

[Synewave]

Gina,

Remember your forum chums when you go to market and make £millions, won't you?

[Gina]

Gina,

Remember your forum chums when you go to market and make £millions, won't you?

But of course What a lovely thought