Driver for 1-Wire sensor bus
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@Nathan-Bertram Although I found a DS18B20 spec telling the sensor can be driven from 3.0 to 5.5 Volts, I recommend the 3.3 V instead of 5V. But more important is to insert a 4.7 kOhm resistor between data pin and GPIO. I think the missing resistor disables proper communication. The sensor id needs to remain the same - it is the hardware address for the 1-wire master to request data. Here is how I connected the sensor:
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@Omega303 ah... I tried hooking up a a 4.7k resistor last night but obviously read the diagram incorrectly: http://monosnap.com/image/ideZC9zI136vSFrAo9LC2747TTcqio not sure what i was thinking LOL -- I'll try again tonight and let you know how it goes. Thank you!
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Hi,
The electronics (diagram) in my case is OK. The issue is that I do not have /etc/modules.d/55 p.....I have listed in a previous post all modules I have with gpio.
Any suggestions ?
Thx,
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@Miguel-Corteguera you'll need to create the file (touch) then insert the line with the correct pin # as instructed above
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@Nathan-Bertram Hi, thanks for the tip. Created the file, restarted the Onion, folder /etc/devices/w1_master_driver now exists, but nothing with DEVICE to be found there.
Any ideas ?
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Now it's working, using +5V and GND and PIN 26. Before I was using + 3.3V. My sensor is a 18B20 with 10K resistor.
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This is how it looks:
root@Omega-276D:/sys/devices/w1_bus_master1/28-0415a810c3ff# cat w1_slave
7b 01 4b 46 7f ff 0c 10 af : crc=af YES
7b 01 4b 46 7f ff 0c 10 af t=23687
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A big thank you to @Omega303, his awesome 1-Wire tutorial is now up on the Onion Wiki: https://wiki.onion.io/Tutorials/Reading-1Wire-Sensor-Data
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SUCCESS - thanks @Omega303 guide looks awesome - finally got it to work after hooking up my resistor correctly this time (using the 5v power source though -- I changed my pin # to 19 instead of 0 and it worked):
awk -F= '/t=/ {printf "%.03f\n", $2/1000}' /sys/devices/w1_bus_master1/28-0215718f9dff/w1_slave
21.500Yeah!
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Using firmware 0.0.6 b275, the temperature DS18B20 works using a 3.3V connection with a 4.7K pull-up resistor on the Data out line. A DS18B20 PAR (PARASITIC version) also works. I connected it using GPIO 26 and I have an OLED to display the time and temperature using some python code.
Ian
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I finally got a chance to try the tutorial, and it worked right away! Thanks Omega303!
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@Ian-Pun Would you be interested in sharing your python code? I am just gettng started with python and have no clue where to start.
Thank you in advance.Dan
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The code in python for the temperature. I adapted from a Raspberry Pi code.
Ian
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@Ian-Pun
That is a great example to work from. Thank you.
Only problem I have now is trying to convert the temp into F.
I have tried adding the calculations in everywhere I can think of and I just get errors.
Any help would be great. I am real new to python programing.Thanks again.
Dan
