DS18B20 one wire temp sensor not being detectec

[carterzrock]

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.

1c.jpg (46.07 KiB) Viewed 1339 times

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.)

2c.jpg (34.89 KiB) Viewed 1339 times

But still the Pi is not sensing it.

3c.jpg (55.08 KiB) Viewed 1339 times

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?

[RST8]

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

[danjperron]

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!

[danjperron]

Try on parasite mode.


DS18B20 pin 1 & 3 to ground.

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

[carterzrock]

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?