Dallas one-wire or RS232 on a prop-1

[Kdavis]

Anyone have code to do Dallas Semiconductor / Maxim one-wire implementation on a prop-1 or BS-1?  I want to read a single temperature sensor and then use part of the remaining pins to trigger an action based on the temperature reading.

I'm hoping to read a Dallas DS18S20 temperature sensor directly or through a DS2480 serial 1-Wire line driver.

I understand that there is a lot of overhead with the 1-wire devices, but I only need to read a single device.

Thanks in advance for your help!

[JonnyMac]

I have a lot of experience with 1-Wire and I can tell you that there is no possible way to do it with a BS1.  The only controller in our line that could do 1-Wire is the Prop-SX. 

How many output pins do you need?  I ask because Dallas/Maxim does make a temperature sensor that you could use, the DS1620, but this takes three pins.

[Kdavis]

I need 3 outputs.   The DS1620 is a possibility, but I understand that it needs to be very close to the micro to be reliable.

Just by way of background, I'm wanting to remotely monitor the temperature in an outbuilding and open 1 or 2 hot water valves to send it more heat as needed.  The third output is to drive a local alarm.

I've seen a reference to an old Nuts & Volts article that did 1-wire on a BS1 but haven't been able to come up with the month & year (much less the actual article...)

What about the DS2480?  Anyone ever interfaced that to a Prop-1?

[JonnyMac]

Really, 1-Wire on a BS1?  I'd love to see that (it's not native, I can tell you, maybe there's something else to it).  Having written most of the Stamp Applications columns for N&V I'm pretty sure it wasn't one of those -- but I have all the reprints from Parallax on my shelf so I'll look through.  Maybe Scott Edwards wrote something as he started the column back in the early days of the BS1.

If you feel like the distance will work via 1-Wire then I see little reason the DS1620 won't work as well (it's just TTL clock signals, and they'll be slow on the BS1).  You could use CAT-5 cable to carry the signals, that would help protect against interference.

I had a look at the DS2480 datasheet and its lowest baud rate is 9600 -- this is above the max (2400) for the BS1.

Q: Could you put the Prop-1 out with the sensor send back the alarm signal?

[Kdavis]

I think I'll try hooking a DS1620 to one end of a box of CAT5e and see what I get off the other end of the wire. 

If I can find the one-wire/BS1 article reference I'll post it.  It may be a few days before I'm back at the office where I found it originally.

[livinlowe]

http://www.parallax.com/Portals/0/Downloads/docs/cols/nv/vol1/col/nv29.pdf

Have a look at this. It isn't 1 wire but talks about using a LM34 or LM35 for remote use. Maybe this will work in your situation.

Shawn

[JonnyMac]

<Smacks forehead>

I should have thought about the LM35, Shawn, as I just wrote about it in my SX/B book!  The LM35 provides temperature as a voltage output; 10 millivolts per degree Fahrenheit, and can measure as low as -50 degrees.

[Kdavis]

I ran across that article yesterday and dismissed it imnediately as having a low cool factor.  Linear IC's?  They'll never catch on... ;)  Perhaps I should go back to what one of my instructors used to ask us:  Do you want gee-whiz or do you want it to work?  Hmm.  So maybe I'll go see if I have any LM34's or 35's in my junk box.

Just for grins I still think I'll see if the DS1626/1726 will cut it reliably over a few hundred feet of 5e.

As always--thanks for all the input! 

--Ken

[Kdavis]

Found the article that references and earlier "one-wire serial slave device" (note that it's not One-Wire or 1-Wire as DS/Maxim would use) so I don't know if this is germain to this thread or not.  This is the link: 

http://nutsvolts.texterity.com/nutsvolts/200411/?pg=82&search=%22nuts+%26+volts%22+%2B%22one-wire%22+%2Bbs1&u1=texterity&cookies=1http://nutsvolts.texterity.com/nutsvolts/200411/?pg=82&search=%22nuts+%26+volts%22+%2B%22one-wire%22+%2Bbs1&u1=texterity&cookies=1