4. Please describe the bug / issue. Attaching any relevant screenshots would be very helpful! Thanks in advance.
My device does not find my sensor any more. Have managed to find its slave address and tried to add it manually but it wont connect.
tried a fresh install but know it does not even auto add like it did the first time. yet it only displayed the disconnected numbers.
Might take a look at the RPi itself and see what it is getting from the sensor.
cd /sys/bus/w1/devices/
ls
cd 28-"put your serial here"
ls
cat w1_slave
if you get something that looks like this, 25 01 4b 46 7f ff 0b 10 65 : crc=65 YES 25 01 4b 46 7f ff 0b 10 65 t=18312
the last number, 18312 in my case, is the temp in milli-Celsius. So in my case it is 18.312°C in my back yard.
At least you will know if the sensor and RPi are working together.
That is disappointing. I wish I could email you another sensor to try. Other than checking to make sure you donât have a break in the path from the RPi through the breadboard to the sensor, Iâm out of ideas.
I have seen that behavior before and it was because I had the sensor wired wrong, reversed polarity I think . Fortunately when I corrected my mistake all worked well.
If it is getting warm, it does sound like reversed polarity to the 18B20. Weird that things worked before.
Do you have a VOM available? Might check the resistor?
I would pull every thing apart at this point, replace what I could (jumpers, resistors, breadboardâŚ) and try again. Iâm fortunate enough to have spare Piâs and 18B20 also, but I understand that isnât the case with everyone.
Sadly I need to go to work, so I wonât be able to check on your progress, good luck,
Slightly on topic here, I have mentioned this before but worth flagging as someone may want to tinker with these ideas:
To super simplify the DS18B20 etc, I am pretty sure you can enable the internal software controlled WPU resistor on the main brain of the Pi and this would make things really nice as you just need to plug the three wires direct onto the GPIO with no fiddling aboutâŚ
Thought is there anyway for anyone who knows how to poke the registers internal settings. I think I even saw a choice of currents ? The Scratch GPIO people do this for digital inputs. It means that just a microswitch is needed and no pull-up or pull-down resistors etc.
I know the 4k7 is not expensive but I use this trick with other microâs and it works a treat for DS18B20, the I2c bus, and for energising other simple two wire sensorsâŚ
~ Andrew
. Fortunately when I corrected my mistake all worked well.