Weatherproof Arduino and components

Projects General Guidance
1

Hi all-

I've been working on a custom GPS device that I got some help on regarding power (thank you again!), and am now thinking about putting it in an actual box. The device has to live outside all year round, in all kinds of weather (including freezing temps), going without power for weeks at a time (the user will bring the battery), and possibly (likely) be dropped on the ground. It also needs to be handheld and, just to make it even more complicated, needs to have a servo-operated trap door.

A little context: the device is for a game called geocaching and the player will use it in a forest; the issue is that the device itself will live in the forest (when not in use, it will be in a waterproof container). The idea is that the player/user will attach the battery, wait for the GPS to get a fix, press a button, and the device will pick a random spot for the user to get to in a particular amount of time. Once the user makes it there (taking the device with), an LED will light up and the timer will start over, requiring the user to get back to the original spot. Assuming the user is successful, a servo motor will turn and open the trap door to allow the user access the log book, which will be inside the device itself.

So the device itself consists of a GPS module, the Arduino (currently an Uno but possibly a Mega because I'm running out of pins and the program may be larger than 32k), a microSD card (to write the coords with the date and time to preserve them in case the user unplugs the battery), an LCD, LED, button, and servo. And all the accompanying wiring. And the log book (standard small spiral notebook).

So the trick is to find/build a container that can hold all this equipment, allow easy access to the battery connector while protecting it from the elements, be strong enough to handle a drop, and if possible I'd like to isolate the area with the log book from the rest of the device so the user can't peek inside and see the equipment.

Might anyone have some thoughts on how doable this is...I've been contemplating welding something custom together, but even if I do that, I'm still not sure how all this equipment will take to the elements...

Thanks for any suggestions!

2

Interesting set of requirements... It might somewhat simplify things if you split housing for the logbook and door opening mechanism into a separate container, wired to the housing with the rest of the electronics. That way you can have a larger logbook and you don't worry about the size and weight of the door opening mechanism making it difficult for the user to work with.

As far as proper enclosures and other rugged and water-proof components, what you are looking for is available. However, with a few exceptions they won't be available through hobbyist type stores, you'll need to look at the larger suppliers like DigiKey, Jameco, or Newark. The only issue with these type of companies is that often if you don't know exactly what you are looking for it can take a while to find it, as their inventories are huge and the classification of some parts can differ significantly between sites. Although of the three I mentioned, Jameco has probably the easiest to browse online catalogue.

3

In addition to the electronics companies (Adafruit BTW resells several cases, and they have an enclosures link on the front page), I would also carefully measure your setup (including batteries), or bring it with you, and check out outdoor companies (EMS, REI), and look for dryboxes. Otterbox and Pelican are the two big names, and they make boxes in various sizes.

4

makes outdoor rated enclosures and not overly expensive.
For example

5

Thanks a lot for the suggestions and links; I'm going through them now. :slight_smile:

As far as the weather conditions go, does anyone have any thoughts about the durability of the ardunio in bad weather (I'm worried about it and the other parts freezing and rendering them non-functional).

6

tachoknight:
As far as the weather conditions go, does anyone have any thoughts about the durability of the ardunio in bad weather (I'm worried about it and the other parts freezing and rendering them non-functional).

Well the IC chips on a standard Arduino will be commercially rated so their operational temperature will usually go down to only 0 C (and that doesn't really take into account self heating). However, since the device will be non-powered most of the time what's more important are the storage temperatures, which have more extreme lower bounds (usually less than -25 C). Also, if you are planning to put the geocache in a really extreme locations you can insulate the enclosure for the electronics, as well as bury it or use an apparatus similar to a solar still/solar cooker to provide some additonal heat.

7

"Well the IC chips on a standard Arduino will be commercially rated so their operational temperature will usually go down to only 0 C"

That is not correct.

The main chip, the '328P-PU is rated -40C to +85C.
The '328P-PN which also frequently seen is rated -40C to +105C.
The '328P-AZ (?) Automitive is rated -40C to +125C. Only in TQFP & leadless package.

Available at Digikey

You would have to select your other components to meet the extremes you anticipate.

8

Far-seeker:
Well the IC chips on a standard Arduino will be commercially rated so their operational temperature will usually go down to only 0 C (and that doesn't really take into account self heating). However, since the device will be non-powered most of the time what's more important are the storage temperatures, which have more extreme lower bounds (usually less than -25 C). Also, if you are planning to put the geocache in a really extreme locations you can insulate the enclosure for the electronics, as well as bury it or use an apparatus similar to a solar still/solar cooker to provide some additonal heat.

Definitely not that extreme, especially considering the more mild winters we've been having in the midwest, USA. I was thinking stuffing the box with the electronics with some sort of insulation material, and lining the external enclosure (probably an ammo can) with something similar. In addition the whole thing would live inside a fallen tree, which would presumably offer more day-to-day insulation from the elements. :slight_smile:

9

Very cool idea! I've made something similar, without the weather proof limitations. Will you have a display? How will you communicate which direction they should go? I love GeoCaching! Been hiding them since 2001.

10

My thoughts were that given people steal the trackables from caches how long would this last in the wild?

11

What kind of GPS module are you using that locks to the sattelites inside a forest?

12

In some neighborhoods it will be very safe, I have tested this theory with other valuables.
The Adafruit Ultimate GPS will work well in the woods. Others will not.

13

CrossRoads:
"Well the IC chips on a standard Arduino will be commercially rated so their operational temperature will usually go down to only 0 C"

That is not correct.

The main chip, the '328P-PU is rated -40C to +85C.
The '328P-PN which also frequently seen is rated -40C to +105C.
The '328P-AZ (?) Automitive is rated -40C to +125C. Only in TQFP & leadless package.
http://www.atmel.com/Images/doc7810.pdf
Available at Digikey
ATMEGA328P-15AZ Microchip Technology | Integrated Circuits (ICs) | DigiKey
ATMEGA328P-15MZ Microchip Technology | Integrated Circuits (ICs) | DigiKey

You would have to select your other components to meet the extremes you anticipate.

I stand corrected...

14

Perhaps you should include some desicant in the box to eliminate condensation.

15

sbright33:
Very cool idea! I've made something similar, without the weather proof limitations. Will you have a display? How will you communicate which direction they should go? I love GeoCaching! Been hiding them since 2001.

Yep, there's a 16x2 display (currently) that gives the lat/lon and the countdown on the second line. Since the player will already have a GPS (they had to use one to get to the original container, after all! :P) it'll be expected they'll use theirs, but I thought including some sort of a toggle switch to go back and forth between the coords they need to get to, and the coords the device thinks it's at.

I've been playing with this idea for awhile and had come up with some variations, but since I'd discovered the Ardunino and making things, the whole idea finally came together; complicated for me, but hopefully the final product will be fun and memorable for the finders.

I started caching in 2009, and have loved every minute of it so far. XD

16

sbright33:
In some neighborhoods it will be very safe, I have tested this theory with other valuables.
The Adafruit Ultimate GPS will work well in the woods. Others will not.

I'm relying on the good nature of cachers to prevent the device from disappearing, but just in case, I have also written into the program a routine that, when it gets the satellite lock, verifies it's within the boundaries of the forest preserve where the cache lives; if it detects it's outside the bounds it will bring up a message "please return me to ..." and go comatose.

I went with the GPS from SparkFun; it's been pretty accurate and fast to lock on so far. I'm taking it on vacation next week in all its breadboard glory and verify that it will work in dense tree cover; if the results aren't great I'll look into the Adafruit one.

17

tachoknight:

sbright33:
In some neighborhoods it will be very safe, I have tested this theory with other valuables.
The Adafruit Ultimate GPS will work well in the woods. Others will not.

I'm relying on the good nature of cachers to prevent the device from disappearing, but just in case, I have also written into the program a routine that, when it gets the satellite lock, verifies it's within the boundaries of the forest preserve where the cache lives; if it detects it's outside the bounds it will bring up a message "please return me to ..." and go comatose.

How about a more nefarious message, such as "uploading GPS coordinates to offsite location", or "GPS tracking enabled", or "LoJack for Cache Activated"

Since you go out there anyway to check the logbook and cache, a hidden Trail Cam might be a good investment.

18

I have built a GPS project that has constant outdoor exposure and I ran into a lot of problems despite having an airtight case. What tends to happen is the moisture in the air from when you seal it condenses when you put it out in the cold. This condensation causes all kinds of problems and it will kill your system VERY quickly. I have done 2 things that work well to combat this. The first is to bake everything in the oven at about 120 degrees for a couple hours to bake the moisture out of everything. Then I seal up the case with just 2 small holes in it. I then blow nitrogen through the case and quickly seal up the holes. I buy the nitrogen cheaply from a local welding supply store. I am also spraying conformal coating over components which to helps prevent problems. I know this sounds like a lot of work and fairly extreme but I have a pile of failed units that show anything less is prone to problems when you leave it for an extended period exposed to the elements.

19

Coud also put some dessicant packs in the enclosure to help with moisture.
Example: