Another try: DS18b20 with errors

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Hi, since an update screwed up my pimatic, I did a reinstall.

Before the reinstall,my ds18b20 worked just fine. No errors in the logfile.
After the reinstall I keep getting a whole bunch of errors:

error [pimatic-ds18b20]: Error reading DS18B20Sensor with hardwareId 28-000007053e71: ENOENT: no such file or directory, open '/sys/bus/w1/devices/28-000007053e71/w1_slave'

I did the follwing:

sudo modprobe w1-gpio
sudo modprobe w1-therm

changed the config.txt:

dtoverlay=w1-gpio-pullup,gpiopin=4
also tried
dtoverlay=w1-gpio,gpiopin=4

and added
devicetree=

Rebootet after every change, but still these errors. I have my temp checked every 6 seconds and see that this error does not occur that much, but in one hour I see about 150 messages.

Any idea?

is the device available at /sys/bus/w1/devices/28-000007053e71 ?

If you get every now and then that error (and the other times a valid temp) i suggest to check the wiring or replace the DS18B20

@leader21 Yes it is.

@koffienl This is the third one that gives these errors…

Ik had the same problem, it was caused by faulty connections in my case.

My situation: Pi with Breadboard. resistance on breadboard,three wires of an ethernet cable of about 5 meter and at the end my ds18b20 is connected and sticked to a metal pipe.

data is on pin 7

Can you test manually the outcome of the DS18B20?
Go to /sys/bus/w1/devices/28-000007053e71 and do a cat w1_slave and see if you got CRC errors in the output. Is it connected to 5v or 3.3v ?
I think it is a combination of cable length , wiring and resistor.

Totall other approach : just toss in a ESP with a DS18B20 connected to it and send the value over wifi to pimatic.

@koffienl said in Another try: DS18b20 with errors:

cat w1_slave

Sometimes cat w1_slave gives
cat: w1_slave: No such file or directory

But… when I go one directory up, go down to 28-… again and then cat: w1_slave gives this result

8b 01 4b 46 7f ff 05 10 3a : crc=3a YES
8b 01 4b 46 7f ff 05 10 3a t=24687

If I wait some time, it gives

the file not found error again. Power is on pin 1 (3,3 v)

The ESP alternative is not an option.

That sounds like a connection problem or faulty sensor.

Try it with 5V you loose some power over 5M of cable.
I have 10m of cable and have to use 5V.

Please try without the devicetree=
It breaks a lot of stuff on the GPIO. Google for it.

@incmve Nope…still the same batch of errors…

@Harry-van-der-Wolf Nope. doesn’t make a difference.

I’ve the same problem
After the last Update I lost one of my 4 DS1b20

error [pimatic-ds18b20]: Error reading DS18B20Sensor with hardwareId 28-0416807e8eff: ENOENT: no such file or directory, open '/sys/bus/w1/devices/28-0416807e8eff/w1_slave'

i’ve checked the cable … same

Detach the DS18B20 and test with breadboard/jumperwires. Working? Your cable is faulty. Still not working? Your DS18B20 is faulty (or you really messed up the wiring )

I connected one of the sensors directly on the breadboard (with 5v) and no errors occur so far. Seems to be the cable or the length of the cable. I don’t know if the value of the resistor can be an issue here?

Resistor should be 4.7K

@koffienl Correct, But I mean, should the resistor be some other value if the cable is very long or are these not related…

I have at least 10M of UTP cable between my Pi and 3 ds18b20 sensors.
I have placed the 4.7K resistor on the Pi side.

In the config.txt I have added:

# 1-wire settings
dtoverlay=w1-gpio

nothing more.

Same for me. 5-6 m UTP cable with 2 ds18b20 on an esp8266. A 4.7K works fine. At a certain moment one of the sensors gave sometimes strange values being 4-5 degrees off (compared to the average). Turned out that the resistor was no longer connected, but even without the resistor it gave correct values in general with sometimes an outlying value.
another ds18b20 on an esp8266 with 6 mtr phone cable: works fine.
I know that my examples concern esp8266 boards and not a pi, but cable length and resistor value are not a cause.

Did you measure the impedance over the cable? In other words: could you have a bad wire in your cable?
Next to that: UTP is Unshielded Twisted Pair: Do you have some source of interference close to your cable (recently)?