# Weather station sensors?

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#### HarveyH42

##### Banned
Wondered if anybody has any cheap/simple solutions or links for some basic weather related sensors. Looking for barometric, temperature, and humidity. None have to be particularly accurate, but should be easy to read/interface with a microcontroller (AVR, of course).

#### 3v0

##### Coop Build Coordinator
Forum Supporter
BeeBop said:
Sorry about that folks. Wetbulb became wet-bulb when I did the spell check and I failed to notice it was in the URL.
But Bill is right. That is a very small budget to do much more then meausre air temp. With the sort of gadget you want to build the web bulb would be a bad idea but it is the only one you can afford.

EDIT: I would LOVE to be wrong on this one.

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#### HarveyH42

##### Banned
blueroomelectronics said:
Problem is the $20 budget won't go far. It's not really a budget, more of a goal. I'll spend what I need to to get one running. Just don't want to get too crazy, just in case I end up making more. I get talked into production work with some of my little gadgets (family, friends, neighbors...), also might be a suitiable project for a 'final-year' student with only a week or two before graduation... Got the wet-bulb link, don't think it's something I can use for this (have to occasionally add water...), also a lot of PVC, maybe$20 dollars worth of fittings. Really only need a very rough measurement,I can scale and adjust in software.

Kind of looks like Futurlec has the best price. Going to search and see if I can find something on the web, that uses the modules. Both do temperature, so with shipping, ought to be around $25. #### kchriste ##### New Member Forum Supporter #### Gayan Soyza ##### Active Member You told that accuracy is not an important so In your case I use LM series Temperature sensors 34 or 35.Works fine & also cheap.Its rated upto 100 - 150C but I have measured temperature more than that. Forgot to tell you can measure the light in the atmosphere too.To determine whether is is night or day time or how dark it is. Use LDR for that, measure the AD reading & apply to the output.Most sun trackers use LDR's as sensors to identify the suns direction. Last edited: #### HarveyH42 ##### Banned mrmonteith said: Thanks for the link. Its the same 'made in china' SHT11/15 that Futurlec has, just a little more expensive. Little cautious that they make no mention of the actual part number, just their house branding. The good part, they give good info on reading from it. I don't do 'C', but should still be able to get some useful bits out of the documentation. Futurlec only has the datasheets. I did find a couple of BASCOM routines for reading the sensors. Didn't see a routine for reading temperature in them, but was just a quick look. Thanks for the other suggestions for windspeed and light sensors. Not really looking to build a weatherstation in the backyard sense, this is more a desktop or shelf. While searching, I ended up at the Edmund Scientific website. Remembered they had really cool, but expensive stuff when I was a kid. Didn't find anything I could use, but found they have something similar to what I'm working on. Theirs is hooked up to the internet, and the lamp color is set by whatever it's set to monitor (doesn't have to be weather). Should have grabbed the link, but it really wasn't useful here. Mine will be stand alone, and take its own readings. Will order from Futurlec when I get from walking the dog. Looks like the best deal, and simplest modules availiable. Kind of a cool bonus that I can take a temperature reading from either the humidity or pressure sensor. Saves me time, money, and I/O pins, likely some code as well. This is coming together quite well. #### HarveyH42 ##### Banned kchriste said: You can use a diode or transistor as a real cheap temperature sensor: http://www.overclockers.com/tips12/ You don't have to use a bridge circuit as the author has done. You just need to bias the diode and an Op-Amp to scale the output into AVR territory. Here is a windspeed indicator that uses no moving parts: http://www.fonema.se/anemom/anemom.html Just got back from walking the dog, checked out the diode temperature sensor. Think I'm going to play with that some. I bought 1000 1n914s a couple years ago for$5, maybe used 30 of them... Will have to do some math, but looks like a single resistor, a capacitor, and the diode are all that's needed for an input to the AVR ADC. Don't need this for the weather project, since I should be able to read the temperature over I2C from either module.

Will have about a three week wait on the modules, so a good time to get on building a simple LCD serial display/terminal. I downloaded the project files a while ago, figured it be a good tool to have, just never got around to it.

#### HarveyH42

I placed my Futurlec order a couple of hours ago. Came to $105.05, with the 'Express Shipping' ($16). It says 3-6 days, where standard shipping was about $9 and 2-3 weeks. Figured I'd give it a shot, still expect about 2 weeks until delivery. I got two of each sensor, but mostly I stocked up on sockets, plugs, and connectors, crystals, and few other odds and ends that I always seem to forget. #### Pommie ##### Well-Known Member Most Helpful Member Harvey, Are you aware that the SH15 is not an I²C device, although it appears to be very similar. Mike. #### blueroomelectronics ##### Well-Known Member$105.05 is slightly more than $20 #### HarveyH42 ##### Banned blueroomelectronics said:$105.05 is slightly more than $20 Yeah, went a little crazy shopping. Still on track for the$20 goal though.

HH10D Humidity Sensor $9.90 HP01D Barometer Pressure Sensor - HP01D$5.50
CRY32 32.768kHz Crystal \$0.75

Should have everything else already. Most of this order was connectors (IDC, header sockets), and a few other odds and ends that are getting scarce around here. Futurlec has the best prices on these, and don't order often.

#### blueroomelectronics

##### Well-Known Member
Sounds like you still need more parts, a microcontroller, PCB?

#### HarveyH42

##### Banned
Pommie said:
Harvey,

Are you aware that the SH15 is not an I²C device, although it appears to be very similar.

Mike.
I bought the cheaper module, but they all say '2 wire SPI'. The sensor in the picture for the HH10D looks different. Should be okay though, the datasheet says there is a Frequency Out pin, and is in the range of 5kHz-10kHz. Need to do some more reading. Also have some BASCOM code for reading these modules, so should be good one way or another.

#### HarveyH42

##### Banned
blueroomelectronics said:
Sounds like you still need more parts, a microcontroller, PCB?
I've got a spare bedroom for a lab, and quite an accumulation of parts...

I make my own PCBs (toner transfer).
I have on hand;
ATtiny11, 13, and 85, but only 8 pin so not suitable
Attiny2313 and Attiny26, either should work for this, thinking 2313 have more
Atmega48, only have 4, and kind still working on that project...

Also have some PICs, no idea why I save them. Pulled them out of something I scrapped, cable box or something.

Hardware shouldn't be a problem, need to read up on SPI and I2C, the MCU datasheets, and get ready.

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