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I have a rasp pi 2 b+ and a temperature sensor DS18B20.

I can't get my ls /sys/bus/w1/devices command to show anything other than w1_bus_master1.

I suspect it is a problem with my set up but I've tried a number of combinations but still no results.

I'm using a 10kOhm resistor, a Vilros cobbler and just updated raspbian (4.1.19-v7+).

I've tried adding this to my /boot/config.txt dtoverlay=w1-gpio

Pics of setup:

The crocodile clips go to the three connections for the DS18B20

The crocodile clips are connected to the DS18B20 [enter image description here

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  • I have no idea what the solution is
    – darkace
    Commented Jul 24, 2016 at 15:52
  • 1
    Have you a meter? If so check the breadboard voltages. Is 5V actually 5V and 3V3 actually 3V3? A common error is to connect the ribbon cable the wrong way around.
    – joan
    Commented Jul 24, 2016 at 16:43
  • I don't currently have one but is there another way to tell if it's the wrong way around? I'll set everything up and try flipping it
    – darkace
    Commented Jul 24, 2016 at 16:58
  • nope, nothing has changed
    – darkace
    Commented Jul 24, 2016 at 17:09
  • Do you have a DS18B20 or a DS18B20-P? Commented Jul 24, 2016 at 23:35

1 Answer 1

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Try this:

  1. Edit your /boot/config.txt line to contain:

    dtoverlay=w1-gpio,gpiopin=4,pullup=on
    
  2. sudo lsmod, check for w1_therm. If it's not loaded, edit /etc/modules to contain:

    wire
    w1-gpio
    w1-therm
    
  3. Use a 4.7k resistor instead as recommended in datasheet. If you only have 10k ones, try to use 2 of them in parallel for a resulting impedance of 5kOhm, for testing purposes.

Reboot after each change. Good luck!

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  • Sounds good. Will check when I'm home tonight but I remember that I currently already have dtoverlay, gpiopin and the lsmod has everything you suggested. Will try pullup and paralleling the resistors!
    – darkace
    Commented Jul 25, 2016 at 10:52
  • @darkace I used kompf.de/weather/pionewiremini.html for setting up my DS1820. It's in German but you should get the point. I also operate my DS1820 in parasite-powered mode so another idea could be to connect the yellow wire that leads to your DS1820 to GND. (edit: works fine in both modes)
    – Domme
    Commented Jul 25, 2016 at 11:01

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