Hello to all!
Last year, I have done a weather station using a Mega2560. Everything went well, until summer season has come, and with it the extreme weather (thunderstorms).
So, let's explain a bit. I have an anemometer (Davis Instruments 6410) for wind speed and direction, a temperature, humidity, rain sensor, and UV sensor. All this information goes to wunderground.com.
The anemometer is mounted on top of my roof, to get accurate readings of the wind speed and direction.
The temperature and humidity sensors are mounted in a radiation shield (in a place with almoust no sun, at 1,5m from the ground). So, the sensors are spread, they are not in the same place.
The mainbox where the arduino mega stands, is in my attic. The power comes from my main UPS, and it has a 5V 2A power supply.
So, everytime a storm comes, my mega hangs randomly... My guess is that it pickes up interferences from air when lightnings strikes nearby. With that in mind... I've changed the original cable from the anemometer with cat5 FTP, and I connect the ground wire to the ground connector in my wall outlet. I've grounded even the entire arm of the anemometer. Since that is the only piece of my weather station that is so high... I guess that its the source of my problems.
The anemometer uses two pins from arduino an analog and a digital one. Is there a way to protect those pins from interferences? What do you guys suggest? Why arduino hangs?
I plan searching for an algorithm to autoreset the arduino, like a watchdog or something... but I know that this is not the elegant solution to resolve this... The problem must be eliminated in other ways...
Any ideas?
Thank you!
Adrian
You have to prevent electrical disturbances from getting to the Arduino, or it will eventually be destroyed. You need protection on every input as well as all the power wiring, and the best grounding possible. You should also put a sharp pointed lightning rod near to and higher than the anemometer.
Something like this might help for the inputs:
Google "weather station lightning protection" for other opinions.
You have wonderful antennas running all around. Please tell us the Arduino also has a ground connection between it and your UPS. Are all your other sensors grounded remotely as well as the anemometer? If your Arduino in a grounded metal box/enclosure?
Paul
Paul_KD7HB:
Please tell us the Arduino also has a ground connection between it and your UPS. Are all your other sensors grounded remotely as well as the anemometer? If your Arduino in a grounded metal box/enclosure?
Paul
No, the arduino has no ground connection between it and the UPS. How can I connect the arduino board to ground?
By ground I guess you dont refer to (- GND) connection!?
The other sensors are not grounded ( they use 4 fires alarm shielded cable, but they are not connected to ground) since I thought it is not necessary because they are not wired so high in the air... should I ground them too?
And no, the arduino is not in a metal box, it is in a plastic box, with the cover open (for ventilation) in my garage attic.( aprox 2,4 meters from the ground).
Thank you!
Ground, ground, ground, metal enclosures and ground those.
Metal enclosures may have ventilation openings - it's just a Faraday cage. No problem there.
Indeed all those long wires are great antennas and will pick up the discharge of lightning (just as any AM radio during nearby thunderstorms). Your anemometer may double as lightning rod, as it's the highest point on your roof. Local grounding is best - typically you can use copper water pipes, that failing copper central heating pipes, as ground connections.
It sounds like you're lucky everything still works.