Weather station thingy

I was playing around with a DL2416T LED display and the Adafruit Data Logger Shield and thought it might be fun to cobble together a little weather station.

I had a BMP085 I2C barometer/thermometer breakout from Sparkfun lying around, as well as a HIH-4030 analogue humidity sensor. I’ve soldered some headers to the proto area of the shield, so i can plug them in and simply unplug them when i’m done playing with it all.

The BMP085 is a 3.3V device. That means that, not only does it need a 3.3V line plugged into its VCC pin, but also requires the I2C data lines to operate at a 3.3V level. Now… you can get by with just hooking it up to a 5V Arduino directly (the I2C lines are pulled up to 3.3V on the breakout board), but that only works if all the devices on the I2C bus are 3.3V. Unfortunately, there’s a DS1307 I2C real time clock on the shield as well sharing it, so that’s a no go.

Since i’ve had a spare Sparkfun logic level converter board in my drawer-box-o-goodies, i’ve soldered that onto the proto-area (that’s the thing chilling out in the shadow of the two haphazardly floating sensor breakouts) and hooked it up to the BMP085 header. Looks neat on top. The bottom, however…

Now that’s what i call a rat’s nest. The code polls the sensors every once in a while (yes, that’s a scientific quantification), blinks the red LED on the shield and then scrolls the relative humidity, temperature and atmospheric pressure data on the Siemens DL2416T display.

I was surprised to find four characters seem quite usable for an application such as this (the display in the photo above is showing nonsense because the shutter opened in the middle of a display refresh). Anyways, the code for the BMP085 and the HIH-4030 conversion formula (temperature compensated) have been shamelessly ripped off of on-line sources, as i was too lazy to do it myself. Finally, here’s a vid:

Oh, and yeah, the Data LOGGER Shield isn’t really LOGGING anything right now. I was too lazy (it’s a lazy weekend, go sue me) to dig through my drawers and find a spare empty SD card.

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