dallas temprature sensors

Other Hardware Sensors
1

I have just set up a layout and a draft programe for a couple of dallas sensors, but the resultant serial print out reads:

"Hi!
Temp0 = -127.00 Temp1 = -127.00Hi!
Temp0 = -127.00 Temp1 = -127.00Hi!"

The temp (which should show a comfortable room temp) does not vary with time. What might I have got wrong??

Any help would be appreciated.

Colin.

2

Draw schematic with pen & paper of how you wired them , take a photo with a cell phone and post that with your code.

3

The value -127 is an indication of the DTCLib that the communication went wrong.

So it seems that the code is working properly but there is something wrong with the hardware connection.

  • wrong pin?
  • no pull up resistor?
  • wrong mode?
  • interference?
  • loose wiring?

So follow raschemmels advice and send us at least the schematic.

4

And the code if you want help. Without both of those there is nothing we can do but say, "oh, that's a shame..." =(

5

Very grateful for your comments.

I am very much a beginner and even simple things can elude me time to time. My apopogies for not seeing the obvious. In this case, it seems that by moving to to a new and unused part of the breadboard (unused) I tightened up the connections - and then everything worked! So, now I get this from my code:

"Temp0 = 21.50 Temp1 = 21.00Hi!
Temp0 = 21.50 Temp1 = 21.00Hi!
Temp0 = 22.00 Temp1 = 23.00Hi!
Temp0 = 22.50 Temp1 = 24.50Hi!"

And with a modified code, even managed to get addresses:

"Requesting temperatures...DONE
2.46
Device Address: 28B49BA90500000D Temp C: 21.00 Temp F: 69.80
Device Address: 28A19DA905000021 Temp C: 20.50 Temp F: 68.90
Device Address: 28C3CAA8050000C7 Temp C: 21.00 Temp F: 69.80
Requesting temperatures...DONE"

Someone needed to point out the obvious!

Many thanks,

Colin.

6

No problem.