Raspberry Pi and DS1820 challenge

[frazelle09]

Hi everyone! i've tried to follow the soldering instructions which construct and small temperature sensing circuit using a DS1820 + a 4.7 resistor and a Raspi.

Here's a photo of the connections on the Pi .. http://webshed.org/wiki/File:Fritzing_rPI_DS1820.png

My problem is that the DS1820 is not recognized by the Pi. Since i suspect my soldering skills more than the Raspi and its detection programs i'd like to know how to use a Multimeter to check the different wires on the circuit to determine (if this is possible) if the DS1820 is still working or not or if i should just unsolder it and try another one.

i have a Commercial Electric MAS830B multimeter and have already tried between + and - on the Pi and see something like 3.3V but am not sure what else to try and what the voltage (watts?, farads?) should result.

Hope someone can lend a hand. Have a super evening!

 

[dorke]

1.The resistor is 4700 ohm not 4.7 ohm (that alone could cause the problem).
2.Can you please post a photo of your circuit?
3.As for using a DMM look here(from 2:10 on).
4.The board you linked to shows +5V ,GND .
Connect the DMM probes and verify that you get
a)About DCV of 5 volts (pins 3 and 1 of the DS1820).
b) Pin 2 should be something in between 0 to 5V (that would depend on the pi activity)
5) I assume you loaded the ds1280 driver into the pi, right?

 

[frazelle09]

Thanks, dorke! i'm really ashamed to post a photo of the circuit - lol - it's really bad. i will if i can, but i don't know what the site's policies are on this. If i can't post it through the site, i'll find a temp site i can post to and provide the link.

Boy, did i blow that info about the resistor... Of course you're correct, it is a 4.7K resistor.

Ug, again you are correct. The pic of the board shows +5, but the other gpio pin on the Pi is the 3.3V - opposite the 5V pin and i tried to be very careful about which pin i connected the + line to - so this is correct in practice at least.

Wow, again, thanks for replying. Really appreciate it.

Have a wonderful evening!

Here's the pics... hope one or two of them are clear enough to see what's going on.

 

[dorke]

Nothing to be ashamed off,we all started at the zero point sometimes...

The connection look o.k.
Make sure there are no "short circuits" between the naked wires.
Use the DMM to test dc voltage at the DS1820 pins as shown.
What are you getting?

 

[frazelle09]

dorke, wow - i really like how you pointed out which wires to probe. +10 for you.

Will start now and report back.

Have a great day!

 

[frazelle09]

O.k. The two outer wires of the DS register 3.27V and the middle wire + GND register 3.26. As an extra, the V between GND and the point below the resistor varies bet. about 3.03V and 1.79V.

Anything else? Does this mean that this setup is alright?

Again, thanks for helping!

 

[frazelle09]

Houston, we have liftoff!

Thanks again to all who helped, esp. dorke. Since the above tests seem to show that all the electrical connections were good, we began to examine the code, only to discover that the wrong file under /boot/ had been edited (config.nxt instead of config.txt - duh). After editing the two files we rebooted and now have 10-0008029a696e w1_bus_master1 under /devices/ correctly listed. Yea!!!

Have a super day! and thanks again for replying.

Edit: i guess i can't edit the title of the thread to indicate [SOLVED]...