My reef pi build and errors (help needed)

pais · Jan 30, 2022

Hello, I would like to share my build and problems with reef-pi, hoping that someone can help me solving. First of all i will explain my setup : Raspberry pi 3 B+ running every function i need on reef pi. I have been trying using many function over the years but the basics I always used is Power Controller and Lighting system. The system worked consinstently from years, since reef-pi 2.2 or similar. Now i run into some problems that i will try to explain, i don't know if they are correlated but i assume they are not.

1) every time RPi shut down (reboot, power outage etc...) the lighting system don't work anymore ( the physical pwm pin outputs constantly 0V), until i set manually pwm mode from LX terminal. Strange : from reboot I see from 'gpio readall' that the pin is ALREADY in pwm mode, but i have to write the line command to 'change' it to pwm (nothing changes in reality). From that setting the lighting works (until the next shut off).

2) using temperature sensors DS18B20, strangely i have good readings until a certain point where i begin to receive -1°C signal and then the sensor is no more found in the wire folder (neither from LX terminal neither from reef-pi). The sensor begins HEATING up too (im testing in mid-air). If i disconnect/reconnect random wires from the header some times it get working again, some times i have to reboot (losing lighting system from what i explained early). The problem occurs when i turn ON/OFF repeatedly Equipement or lights, but not always, some times it seems random error.

Having explained the problems, if you have further questions please ask, i will upload some photos of circuit connections, but i don't think it's related to hardware problem. I have tried purging reef pi and back-grading to older versions but errors still occurs so it doesn't seems to be related to sofware ... Please help!

theatrus · Jan 30, 2022

A "Warm" DS18B20 is usually a sign the device has had water ingress issues (many die this way). Try replacing the sensor.

robsworld78 · Jan 30, 2022

As some things are intermittent it might be worth pulling out each header pin wire and wipe the pin with sand paper or slide in and out a few times as they've been like that for years.

attiland · Jan 31, 2022

Just to add to the above I would not power the Arduino via usb Although it is not clear what it is doing could use too much power.
You mentioned rapid on off equipment before issue comes and it could well be power issue.
I would replace the DS18B20

pais · Jan 31, 2022

Thank you everybody for your suggestions, the DS18B20 are 2 new probes and never submerged in water yet (bad experience with older ones...), I'm trying to make them really waterproof with cianoacrylate glue before submerging. The problem occurs for both sensors in same moment, and they start heating up (not only "warm", if you keep in hand they become very hot). I will try to check all pin header and upgrade power supply to the Rpi that sometimes gave me low voltage error. A change i have done is to power up the DS18B20 through a 3.3 V channel instead a 5V, now it seems working better (no experienced issues until now).

theatrus · Jan 31, 2022

pais said:
Thank you everybody for your suggestions, the DS18B20 are 2 new probes and never submerged in water yet (bad experience with older ones...), I'm trying to make them really waterproof with cianoacrylate glue before submerging. The problem occurs for both sensors in same moment, and they start heating up (not only "warm", if you keep in hand they become very hot). I will try to check all pin header and upgrade power supply to the Rpi that sometimes gave me low voltage error. A change i have done is to power up the DS18B20 through a 3.3 V channel instead a 5V, now it seems working better (no experienced issues until now).

If they're very warm, they're likely either shorting across the power/GND pins, or the data/GND (or even data/power) pins. Pulling this much power from the Pi supply will show the low voltage issues.

Things to check:
- The sensors just with power don't get warm
- The pull-up resistor (4.7k) is connected to the same power supply as the power pin (and present!)
- Nothing else is shorting the data pin to the power pin.

If you can rule out the circuit you've built its possible the sensors just have an internal short when they were made. Expect minimal testing to have occurred at the price point they're offered at.

dadarara · Feb 17, 2022

my experience with the Temp sensors (have 2) is that they are periodically stop sending data simultaneously (getting - 1c, and errors in Reefpi)
I believe the quality of these ALIEXPRESS origin sensors is the issue.
When I see this error I simply disconnect one of the two sensors and connect again. will check if they heat at this point. never did check it.
I have a way for a solution : https://github.com/SkullKill/onewireMonitor
this is a running script that will reset one of the GPIO pins of your choice when it detects that they are missing.
so this should be the POWER pin to the sensors. and it should be 5v.
the reason i DID NOT use this , is that I am using the ROBOTANK excellent board and I have only the POWER BAR pins to play with. which are 3.3v and not 5v. I tried to drive the TEMP sensors with 3.3v but they dont work. So the next step for a solution for me would be the raise the 3.3v to 5v . I stop the testing as this will demand additional circuitry and it becomes problematic.

will need to think some more.

pais · Feb 17, 2022

Thank you for your experience, as you said dadarara I think quality issues induce problems in these cheap sensors. I discovered my sensors works well with 3v3 power supply and never failed again from that. I'm beginning to explain a theory for failure concerning your reported experience: maybe bad manufacturing allows in some circumstances for internal shorting pins (like suggested by theatrus) caused maybe from thermal dilatation , that for my experienced was more evident when using 5v alimentation (due to more heat produced at sensor). When you unplug the pin you give the sensor possibility to dissipate heat and return to original form (non shorted pins). thank you very much for the script: I will use it in case something got wrong again !