{"id":906,"date":"2014-03-29T18:53:18","date_gmt":"2014-03-29T16:53:18","guid":{"rendered":"http:\/\/www.nico-maas.de\/wordpress\/?p=906"},"modified":"2014-03-29T18:53:18","modified_gmt":"2014-03-29T16:53:18","slug":"rasppi-really-poor-mans-ds18b20-temperature-sensor","status":"publish","type":"post","link":"https:\/\/www.nico-maas.de\/?p=906","title":{"rendered":"[RaspPi] Really poor mans DS18B20 Temperature Sensor"},"content":{"rendered":"

As I had to quickly come up with two DS18B20 Sensors for the Raspberry Pi, I decided to built them \"quick and dirty\" without any breadboard. It is not the most beautiful nor the best way, but it works out quite well. With one exception: It seems like the sensor is too near to the Pi and picks up heat from it :\/. Anyway, here are some photos:<\/p>\n

\"2014-03-24<\/a>
\nThat is how it would look like later.<\/p>\n

\"2014-03-24<\/a>
\nAdding some female header to the base. We need 5 Pins for that. The first pin is going to be connected to 3,3V, the fourth to the GPIO Pin 4 and the fifth to ground. So just cut the pins 2 and 3 from that header.<\/p>\n

\"2014-03-24<\/a>
\nAdd an resistor to pull the Data Pin high to 3,3V. You should use an 4,7k Ohm, but anything between 4,7k - 10k Ohm should work out. I used an 10k Ohm here.<\/p>\n

\"2014-03-24<\/a>
\nSolder the two pins of the resistor to Pin 1 and Pin 4. Do NOT short with Pin 5!<\/p>\n

\"2014-03-24<\/a>
\nAdd some silver wire to the fifth Pin.<\/p>\n

\"2014-03-24<\/a>
\nSolder the DS18B20 to the Pins. Watch out for the curved side of the Sensor, it has to face upwards!<\/p>\n

\"2014-03-25<\/a>
\nI choose to secure the whole sensor against short circuits and stuff with hot glue. Looks ugly, but does the trick.<\/p>\n

\"2014-03-25<\/a>
\nLast thing is installing the sensor in the left upper corner of the GPIO Pins of your Raspberry Pi.<\/p>\n

After booting you have to activate the One Wire protocol like this:
\nsudo modprobe w1-gpio
\nsudo modprobe w1-therm<\/code><\/p>\n

Then you can read your sensor by using this command:
\ncat \/sys\/bus\/w1\/devices\/28*\/w1_slave<\/code><\/p>\n

If you want to get your reading nicely formatted, you should install bc with
\nsudo apt-get install bc<\/code><\/p>\n

and use this code:
\necho \"`cat \/sys\/bus\/w1\/devices\/28*\/w1_slave | grep t | cut -d= -f2`\/1000\" | bc -l | awk '{printf \"%.2f \\n\", $1}'<\/code><\/p>\n