maycom007
Posts: 4
Joined: Sun Jun 28, 2015 8:14 pm

DS18B20 Temperature Sensing

Sun Jun 28, 2015 8:28 pm

Hi,
I´ve a DS18B20 sensor connected to my RASPI 2 B.
My OS is: Linux raspberrypi 3.18.10v7-aufs #1 SMP PREEMPT Wed Apr 1 00:07:44 CEST 2015 armv7l GNU/Linux

Connected to my PI with 4K7 resistor as shown in "tons" of HOW TO....
Have 3.3V measured in to the sensor. Wiring is OK....

BUT.... I´m not able to detect the sensor..... main source is the following:
http://www.projects.privateeyepi.com/ho ... ng-ds18b20

Any help welcome :)
-thanks

maycom007
Posts: 4
Joined: Sun Jun 28, 2015 8:14 pm

Re: DS18B20 Temperature Sensing

Sun Jun 28, 2015 10:01 pm

Hmmm....
Have a 2nd pi2 B..... and a 2nd. DS18B20....
Did a fresh install and, HEY!! it work!!

The new install returns (uname -a):
OS is: Linux raspberrypi 3.18.11-v7+ #781 SMP PREEMPT Tue Apr 21 18:07:59 BST 2015 armv7l GNU/Linux

- trying to swap sensors.....

wernert
Posts: 10
Joined: Fri Jul 25, 2014 11:45 am
Location: New Zealand
Contact: Website

Re: DS18B20 Temperature Sensing

Mon Jun 29, 2015 11:10 am

Did you use the same resistor on both? I also had cases where the RPi would not detect the sensor until I reboot or change the resistor value etc, and I found that when I used a slightly smaller resistor it worked fine.

I also recently went through all the same pains while I implemented my EasyPeasy (https://www.indiegogo.com/projects/easypeasy) project. It reads in temperature from a DS18B20 , but it can also read the temperature remotely via RF from a low cost Arduino based sensor. In my personal opinion I preferred using the Arduino as the interface to read the DS18B20 sensor and then send it wirelessly to the RPi, rather than using the RPi to read the temperature sensor directly. It just worked much more reliable and meant I could keep the RPi in one central location where it has LAN access and place several Arduino sensors in remote locations.

maycom007
Posts: 4
Joined: Sun Jun 28, 2015 8:14 pm

Re: DS18B20 Temperature Sensing

Mon Jun 29, 2015 2:24 pm

Hi wernert,
Have tested both my DS18B20 on the "new" raspi. Works fine :)
I'll try to swap power supply on my 2nd raspi.....

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