Raspberry Pi Forums

This was all using the Pi 2 B v1.1
I have connected the sensor as you can see below. I have included the pullup 4.7k resistor. I have modded the boot/config file. Followed by a "sudo reboot". See bottom line.
(just noticed the overscan left ="" - i corrected that and it doesnt seem to be causing issues.) But still the Pi is not sensing it. Ive used a multimeter to check that
-the wires are connected. Legs of the sensor to the gpio pins are good.
-The 3.3v pin is 3.3v compared to the GND pin
-the 4.7k resistor is actually 4.7k

Ive tried three different identical sensors.

Ive tried adding ",gpiopin=4" to the end of the boot/config line.

All this was all completed after a "sudo apt-get update" followed by "sudo apt-get upgrade".

Still no joy

Any ideas?

if you:
sudo modprobe w1-gpio
sudo modprobe w1-therm

then look in /sys/bus/w1/devices
there should be an entry something along the lines of
/28-03146c6b24ff/w1_slave
the first part is a serial number, so will vary between your 3 sensors.

Joe

What kind of DS18B20 you have

DS18B20 or DS18B20P?

"P" means parasite mode.

If you have a DS18B20P the Power is on the DATA line. Your setup won't work!

Try on parasite mode.


DS18B20 pin 1 & 3 to ground.

Add pullup="y" in option to enable parasitic mode

danjperron wrote:Try on parasite mode.


DS18B20 pin 1 & 3 to ground.

Add pullup="y" in option to enable parasitic mode

Are you suggesting i add
dtoverlay=w1-gpio-pullup,gpiopin=4,pullup=y
To the boot/config file to enable parasite mode?