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  • Author Author: verrverr
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Pas Home / 1-wire vs Tektronix oscilloscope

verrverr

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Hello, this week I did a lot of testing and debugging with the oscilloscope. I try to see and solve the problem of my network of temperature 1-wire sensor.

 

 

I try first to change my connection to the 5v and 3.3v use, I also change the cable connection together. Using the 5v is really not advise for raspberry pi but its still work reasonably well for 6 months.

Result : failure no captor are detected

 

imageimageimageimage

 

Then I tried to change the way power sensors using the parasitic mode. As some suggest me in another post

Result : no difference, no captor detected

 

Here are some screenshots of what I normally should have as working signal

With 1 sensor on 3.3v

imageimage

With 1 sensor on 5v and level switcher

imageimageimageimage

According to this guide Guidelines for Reliable Long Line 1-Wire Networks - Tutorial - Maxim my curve have slow rise time and maybe some reflected problem


Finally I retest on 5v but with a level converter https://www.adafruit.com/products/757 to send only 3v on raspberrypi port

Result : Success all captor are detected and all communicated data are correct

imageimageimageimage

Interesting curve. Yellow is the 5v side data and Blue the converted 3.3v result

image

 

I'll do other tests removing resistors supposed to improve communications and see if it really helps and I will also make a soldering version on a perma-proto board.

Do you see anything else that could improve my circuit?

 

Old schematic

image

 

New improve schematic

image

Parents

  • First, thank you for your advice


    I dont know the capacitance per foot of my wire. I use existing wire available in the wall use by standard low power thermometer. The cable size is 18avg. It is recommended to use the network cable cat5.


    I will try with lower resistance in my next test.


    I keep DS2482 or DS2482S-800+ option in a backup plan.


    The white background graph are take with OpenChoice Desktop snapshot and i not found setting for the backgtound. Next time i will use more the save option of the oscilloscope. I forget these images and this is why you see some picture with my phone. I also recently found the option for loading .cvs data file with OpenChoice Desktop.

Comment

  • First, thank you for your advice


    I dont know the capacitance per foot of my wire. I use existing wire available in the wall use by standard low power thermometer. The cable size is 18avg. It is recommended to use the network cable cat5.


    I will try with lower resistance in my next test.


    I keep DS2482 or DS2482S-800+ option in a backup plan.


    The white background graph are take with OpenChoice Desktop snapshot and i not found setting for the backgtound. Next time i will use more the save option of the oscilloscope. I forget these images and this is why you see some picture with my phone. I also recently found the option for loading .cvs data file with OpenChoice Desktop.

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