These
posts describe a working set-up of following component:
- Raspberry Pi 3
-
DS18B20 (1-Wire Digital Temperature Sensor)
-
Eclipse Kura (Eclipse Project: Framework for IoT Gateway)
-
Eclipse Mosquitto (Message Broker for MQTT)
-
Eclipse Paho MQTT (Eclipse Project: MQTT Client)
The
post primarily discusses how to make above components work, however,
we will try to provide the relevant resources throughout the posts.
We
start off with connecting DS18B20 and Raspberry Pi, there are a
number of online resources which helps to understand 1-wire sensor
and how to connect them to Raspberry Pi, following are the two which
I used:
Above
links explains it in a detailed way, we instead look at another
issue: in some cases, we come across an error when following command
is executed: (discussed on the above links)
cat
w1_slave
Error: w1_slave: No such file or directory
Generally when sensor is connected successfully and is working
properly, upon executing following commands:
cd /sys/bus/w1/devices/
ls
The list should show your sensor(s) as a directory with its name
starting with ‘28-’, the name itself is a combination of
characters and numbers. I experienced that in situations where sensor
is not correctly working in fact not connected properly, the sensor
directory name is although, a combination of characters and numbers
but doesn’t start with ‘28-’. In these situation command: cat
w1_slave returns the above error.
The source of the error, as mentioned earlier, could be incorrect
connections, connecting wires not working properly, incorrect GPIO
connections (Caution: As always be careful with GPIO connections).
I have attached some images from my working set-up below. I used
10K ohm resistor in my setup and Dallas Digital 1-Wire Temperature
sensor.
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