I have five DS18B20 thermometers in my greenhouse connected to my
Raspberry Pi Model B Plus Rev 1.2.
It is running
Raspbian GNU/Linux 10 (buster).
Here you can see that the two thermometers which are ~15cm under the soil report 0.187°C and 0.875°C, which is reasonable as it has ~-5°C outside.
The three other sensors which are in the air report bogus values. This is due to some incompatibility with the software with my old pi, as
- my pi zero with the exact same hardware (apart from being a zero instead of a b+, meaning: same little board with a 4.7kΩ resistor also driving multiple thermometers connected to the same gpio pins) and software setup can read negative degrees
- it could read negative degrees just fine when I was still running minibian (on the b+) and not the latest version of raspbian (on the b+)
root@raspberrypi:/sys/bus/w1/devices# for d in 28-* > do > pushd $d > cat w1_slave > popd > done /sys/bus/w1/devices/28-01191a0f798a /sys/bus/w1/devices b4 ff 4b 46 7f ff 0c 10 b5 : crc=b5 YES b4 ff 4b 46 7f ff 0c 10 b5 t=4091250 /sys/bus/w1/devices /sys/bus/w1/devices/28-01191a40cfa1 /sys/bus/w1/devices 0e 00 4b 46 7f ff 0c 10 71 : crc=71 YES 0e 00 4b 46 7f ff 0c 10 71 t=875 /sys/bus/w1/devices /sys/bus/w1/devices/28-01191a42fc0d /sys/bus/w1/devices 03 00 4b 46 7f ff 0c 10 0d : crc=0d YES 03 00 4b 46 7f ff 0c 10 0d t=187 /sys/bus/w1/devices /sys/bus/w1/devices/28-01191a4d5e9c /sys/bus/w1/devices 9a ff 4b 46 7f ff 0c 10 a4 : crc=a4 YES 9a ff 4b 46 7f ff 0c 10 a4 t=4089625 /sys/bus/w1/devices /sys/bus/w1/devices/28-01191a63a353 /sys/bus/w1/devices ad ff 4b 46 7f ff 0c 10 88 : crc=88 YES ad ff 4b 46 7f ff 0c 10 88 t=4090812 /sys/bus/w1/devices
Here is an image showing that the sensors are not broken, when holding them in my hand they report data as they get warm and go above 0°
- Who do I have to send a bug report to?
- Is there a workaround?
- Can anyone that can read hex and knows their way around integers tell me how to extract the correct values out of the code block above?