Temperature Problem

[D396]

I have a DS18B20 hooked up to a 28x1 on the one wire bus and I get a zero reading every time
here is the basic code :

main:
readtemp 7,w1
if w1 < 127 then ' test for positive temperature reading
sertxd("-",#w1)
else ' else temperature reading is negative
sertxd(#w1)
endif


wait 1
goto main

Thanks for any help you can give
here is a picture of the breadboard:

 

[eclectic]

D396

I'm sorry, but I find the circuit/photo a little confusing.

What happens when you connect the circuit
exactly as shown in Manual 2, page 154,
and use the program from the same page?

The DS18B20 normally works perfectly.

e

PS
It is much easier if you can use the
Manage Attachments
option
then Attach JPG files

from the Reply page.

Edit
Cross posts. I was replying to the original question

 

[Technical]

You have the V+ and 0V on the sensor the wrong way around (unfortunately this may have killed it....but you might be lucky)

 

[D396]

Thank you so much the data sheet was backwards

 

[Technical]

Or you read it backwards! Sometimes it is hard with original manufacturers datasheets to know if they are drawn 'from above' or 'from below' . The diagram under 'readtemp' in part 2 of the PICAXE manual should be clearer for you.