Comments on: One Wireduino made easy

By: Edwin de Graaf

Edwin de Graaf — Thu, 28 Jan 2010 22:28:35 +0000

In your Arduino code you need to add a leading zero to the frac variable if it is less than 100.

Thanks a lot for documenting all this, it has allowed me to get something that works as a starting point.

By: ScaredyCat / Andy Powell

ScaredyCat / Andy Powell — Tue, 14 Apr 2009 07:31:29 +0000

Trevor,

The limitation on how many 1-wire devices can be in a chain is not so much the bus it’s more to do with the memory of the arduino. I’ve worked around that problem because I’m actually using wireless nodes with a number of 1-wire devices attached. Each node handles a few sensors for the area they are in. This saves me from having to drill holes in walls or ceilings. I’ll write it up but essentially it’s just xBees and 1-wire chips on an arduino.

If you want to add a lot of 1-wire devices and you are not using the arduino then you might want to look at not using parasitic power as per my diagram. Using local power will allow for longer cable runs and so more sensors on the bus

By: trevor

trevor — Tue, 14 Apr 2009 07:19:59 +0000

Hi,

Yes, your answer was what I was asking for.

I’ll give it a try and see how I get on. I thought you might have a practical knowledge of what number of 1-wire devices can be placed on the bus.

Thanks,
Trevor

By: ScaredyCat / Andy Powell

ScaredyCat / Andy Powell — Wed, 08 Apr 2009 07:26:08 +0000

I’m not sure what you’re asking here Trevor, I think you might be wanting to daisy chain more sensors. If that is the case then first of all you don’t need to change any code at all. The code will scan for multiple chips and return the values for each. The 1-wire id is printed followed by its value . For the wiring you simply repeat the connections as per the first diagram. I take 2 wires GND and DQ to the next chip from the first and link the VDD to GND near the chip. Hope that clears it up for you..

By: trevor

trevor — Wed, 08 Apr 2009 02:40:49 +0000

Good resource,

How temps can be measured on one bus??

By: ScaredyCat / Andy Powell

ScaredyCat / Andy Powell — Thu, 05 Mar 2009 22:43:50 +0000

Thanks for spotting that one Mike. Looks like I’d lost those while editing for some reason.

By: Mike

Mike — Thu, 05 Mar 2009 21:49:37 +0000

Hi,
thanks for a nice piece of code, works just fine.
I believe there is a small bug in line 9&10
You can get OneWire library from here http://homepage.mac.com/wtpollard/Software/FileSharing7.html, just unpack it to ‘…\hardware\libraries’ folder inside Arduino main folder.

By: ScaredyCat / Andy Powell

ScaredyCat / Andy Powell — Sat, 28 Feb 2009 16:21:48 +0000

Sorry I didn’t get to you in time David but I wasn’t near a PC

By: David Powell

David Powell — Sat, 28 Feb 2009 12:51:29 +0000

I figured it out – I didn’t pay close enough attention to the schematic at the top of your page. I had assumed that the internal pullup resistors were being used, and left out the one you showed in the diagram. Doh!

By: David Powell

David Powell — Sat, 28 Feb 2009 01:53:53 +0000

Man, I can’t get this to work at all. I haven’t done any C programming in years, so it’s probably me instead of the code. When I run the sample.c test program, it just spits out “No more addresses” over and over, unless I disconnect the DS1820. In that case it prints “R=0 0 0 0 0 0 0 40 CRC is not valid!” over and over.
It seems so simple, what am I doing wrong? Looking at the OneWire.cpp file, I would swear that the search method wants an 8-bit byte pointer for input, but you’re sending it a pointer to an 8-element byte array. But like I said, I haven’t done any C in years. Any idea what I’m doing wrong?

By: ScaredyCat / Andy Powell

ScaredyCat / Andy Powell — Wed, 11 Feb 2009 15:10:05 +0000

Josh,

I’ve hope to have answered your question on how to get the data into cacti by adding to the bottom of the article.

As for the number of devices, as yet, I’m unsure but I’m going to get my hands on some more DS1820′s to see when/if any issues occur. I have to say though getting >=20 is not going to happen that soon, perhaps another 5-10. So far I’m testing in a single chain, things may be different if using multiple chains off different io ports, switching between them as needed. More experimentation is required. Running out of memory is likely to be the main problem.

By: Josh

Josh — Wed, 11 Feb 2009 01:42:21 +0000

So a couple questions – how are you getting the data into cacti from the arduino? That looks cool. Also – how many devices can be on the 1-wire bus? I’ve seen a bit of conflicting information on this – one source uses a phanderson one wire interface chip, but I’ve done a little 1-wire with just the arduino. I’d love to be able to hang 20 sensors off an arduino.