So a little back story on the project.
I designed a climate control system for my oyster mushroom grow room. There is a dht11 sensor that is used to maintain humidity and an RTC module that controls a light timer and fresh air fan.
This whole system was working great until last night when I noticed the fresh air fan not turning on in its designated times.
Now I know it's not a programming bug because I've been running the controller 24/7 for about 2 weeks now.
I ran through some minor troubleshooting and here are the results finding things that are NOT broken.
- The power supply to the fan
- The fan itself
The relay shield that is run by my mega 2650 is the sain smart 4 channel solid state shield. The led to the corresponding relay assigned to the fan timer does not light up when activated but instead faintly blinks. This is across the board as well. I reassigned the puns to test it in all 4 channels and it has the same results (led only faintly blinks).
I tested the outlets with my voltmeter and had 0 power at the outlet so the relays are not tripping for the fan when the program switches them on. On the flip side my humidity pump works fine. Even when the fan was assigned to the same relay the light only blinked when the fans "kicked on" but turned on bright and red when the humidity pump activated.
The serial monitor is printing time so I'm assuming my RTC module is fine.
Any suggestions from the crowd?
The picture is an example of how it looks when everything IS working.
Hi,
Did the fan timing begin working again after you reset the controller?
If so, are you using milli's for your timing and delays?
Not sure if this is your problem, but with information supplied!!
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
How are you supplying power to the relay PCB?
If you leave the fan disconnected does the LED still flicker?
Tom... 
Cameronmw:
Now I know it's not a programming bug because I've been running the controller 24/7 for about 2 weeks now.
Any suggestions from the crowd?
Yes. Do not make assumptions if you are hunting an error.
TomGeorge:
Hi,
Did the fan timing begin working again after you reset the controller?
If so, are you using milli's for your timing and delays?
programming - How can I handle the millis() rollover? - Arduino Stack Exchange
Not sure if this is your problem, but with information supplied!!
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
How are you supplying power to the relay PCB?
If you leave the fan disconnected does the LED still flicker?
Tom...
I tried reseting the module several times. I also tried reassigning the fan timer to different relays on the board and still the same results.
The relay module is powered from the arduino 5v out pin.
I will have to try to draw a schematic when I get home.
As far as how I'm controlling the timing:
This is determined by reading the RTC module. It is set for the minutes 0-5 and 30-35.
This module worked flawlessly up until now. This is why I suspect a problem in the electronics and not the program. I reset the module daily when I hook it up to my computer to see the serial print.
I'm suspecting a problem in a solder connection or maybe a parasitic power draw on the board, keeping the arduino from spying 5v to the relay. Is this feasible?
I'm suspecting a problem in a solder connection or maybe a parasitic power draw on the board, keeping the arduino from spying 5v to the relay. Is this feasible?
Try different arduino pins. You'll find yourself.
Can we see the code and a schematic ?Its like shooting arrows in the dark.
-Malhar
Here's what I suggest -
Make a simple test program that "blinks" the fan on & off every few seconds. Then, check the Arduino's output, the DC driver board's inputs & outputs, and the relay's input (coil voltage) and output (fan voltage). You should be able to track-down where the voltage stops switching.
Even when the fan was assigned to the same relay the light only blinked when the fans "kicked on" but turned on bright and red when the humidity pump activated.
I have no idea what you're talking about... Are those LEDs on the sain smart shield, or what? If they are on the shield, are they on the input or the output?
Try replacing the fan with a light bulb and see what happens.
So I kind of at a loss for words. I started testing some of the circuits last night and it just randomly started working again. I will keep a close eye on it and keep everyone posted.
As soon as I get a chance this weekend I plan on drawing that schematic so you guys can critique (be gentle, my first project) and maybe you can give a better diagnosis.
I also have a new relay shield (not solid state) to replace the one I'm using now. A power surge fried the resistive fuse on Channel 4 a while back and I'd like to start using that again.
Cameronmw:
. A power surge fried the resistive fuse on Channel 4 a while back and I'd like to start using that again.
Are you sure it was a power surge ?
Waiting on your circuit diagram.
Sometimes circuits just work at their limits.
Because it worked for two weeks does not mean it was a good design.
Boardburner2:
Are you sure it was a power surge ?
Waiting on your circuit diagram.
Sometimes circuits just work at their limits.
Because it worked for two weeks does not mean it was a good design.
Pretty sure it
Boardburner2:
Are you sure it was a power surge ?
Waiting on your circuit diagram.
Sometimes circuits just work at their limits.
Because it worked for two weeks does not mean it was a good design.
Pretty sure it was a surge. I had a radiator heater hooked into channel 4 and it was just too much draw on the system. Luckily it's warm enough now that I don't need it.
I will probably post the diagram tomorrow when I can actually sit down and spend some time on it. I'm no engineer so I'm sure it's not perfect but I'm not expecting perfection, just functionality.
