Temperature sensing with LM234-Z3 and SECU16

[Brian Raynor]

I have a bunch of LM234Z-3 temperature sensors and would like to be able to hook this into the analog input of an SECU16 to monitor temperature with my Ocelot.

Does anyone know of a simple circuit to do this? The SECU16 can sense resistance level changes.

And after the circuit, can you provide the formula to convert from the Ocelot value (0-255) to the actual temperature (either C or F)?

[jsteed]

I looked at the data sheet for these and am afraid that I can't be of much help with deciphering/deciding the circuit needed to read these. I use the LM34 which is a bit easier to work with since they produce a voltage output rather than current.

I believe that the secu16 can work with a mA current input but you might need a resistor at the input as well to convert the current source to a voltage reading. Your best bet for an help with the circuit is probably on the Cpuxa mailing list, since those guys know the quirks of the Ocelot inputs. You can sign up for the list at www.futurestandard.com.
If you do get the circuit figured out, I can help with converting the input to a temperature but the basic gist of it would be similar to this:
(# steps)*(F/10 mV)*(5v/255 steps)
# steps = secu16 reading
F/10 mV = output of the LM34 (1 deg F causes 10 mV output change)
5v/255 = A/D conversion of the secu16

jim

[Brian Raynor]

Jim,

Thanks for the info. I'll try that list, have been off it for a while...

I have a bunch of these sensors that came off the old Intel "Hobbes" boards. Basically these were ISA boards that more or less was a complete 8086 based computer and were used for server management (report temperature, voltage usage, etc of the server and could dial out to report errors). Have about 5 of the guys that I would love to be able to use for HA (complete with nice batteries), but I really don't want to mess with writing software for them (that was 7 years ago).

Thanks for the help!

[srodgers]

http://www.hometoys.com/htinews/dec9...sen/hansen.htm