Graphing Vivarium Humidity and Temperature Using RRDTool

The temperature and humidity monitoring of my vivarium is really coming together.  I'm recording a timestamp, humidity, and temperature to an SD card every minute using Adafruit Industries' SD card breakout board:

Components on breadboard

The SD card is sneaker netted to a computer running RRDtool and used to produce graphs to give a sense of how the environment looks across the day.  The temperature nicely lines up with what I'd expect given the way the thermostat on the house heating is set up:

24 Hours of Temperature Data

Tracking Humidity and Temperature with an Arduino

Having added a realtime clock to my Boarduino, I'm now on to measuring the humidity and temperature inside the vivarium.  This iteration displays the current reading along with the time on the LCD.  Eventually, I plan to capture the data so I can graph how these are changing over the course of the day.

Masdevallia with AM2302 Temperature / Humidity Sensor

Incremental Bill of Materials
New to this step is a temperature / humidity sensor from Adafruit Industries.  I went with the AM2302 since I think the DHT22 will give a reasonable amount of accuracy and I liked the larger plastic housing.  I did end up soldering a scrap length of CAT5 cable to the sensor's wires to make the wires long enough to get out of the vivarium to the board.

Description	Cost
AM2302 (Wired DHT22) Temperature-Humidity Sensor	$15.00

(The full bill of materials is provided at the end of this post)

Wiring

Components with Logical Connections

1. The AM2302 runs on 5V along with the LCD and RTC.
2. The ground line is connected to common ground.
3. The data line is connected to digital pin 2 on the Boarduino.

Code
Initial setup of the sensor involves creating a new DHT object and passing in the data pin and sensor type as parameters.
Each pass through the loop, read the values from the sensor. The sensor only produces readings every two seconds, so this might be better reduced to only reading every 5 seconds or some other arbitrary interval.
Full source code is available on github:
https://github.com/dmalec/Project-Masdev/tree/master/masdev_temp_humid

LCD Showing Time, Humidity, & Temperature

Full Bill of Materials

Description	Cost
AM2302 (Wired DHT22) Temperature-Humidity Sensor	$15.00
Boarduino	$17.50
FTDI To USB Adapter	$14.75
16x2 LCD	$9.95
LCD Backpack	$10.00
Real Time Clock (DS1307)	$9.00
12V 6A Power Supply	$8.62
Total	$84.82

The next step is recording the temperature and humidity readings to an SD card and graphing the data using RRDTool.

Masdevallia Madness

I'm, at best, a dabbler in growing any one kind of plant.  So, when I saw an unusual orchid on the sale table at the local nursery, I really had no idea what I was getting myself into, "How different could it really be?".  Several months later, I've finally had to admit the answer is "Very".

Orchidus Angrius

All the orchids are watered together - within days, this one resembles a rhododendron in winter; clearly not happy with the humidity levels.  Off to the bookcase to dig out Cullina's Understanding Orchids and look up Masdevallia [Masdevallia Heathii (veitchiana 4N x ignea 4N) to be specific].  This is not going to be easy, but it looks like it will be fun.

But will the locks hold in the orchids?

First step was getting some way to keep the humidity around the orchid at a significantly higher level than I've had it.  Shopping around, I decided to give the Exo Terra 12 x 12 x 18 Vivarium a try.  Too soon to say if it's big enough or the right pick for the job, but I liked a number of features:

• Front access via double doors.
• Good airflow (my thinking is that it will be easier to reduce airflow than to try and give better airflow to a more sealed design).
• Openings at the top back designed for routing wires (should be handy as I add sensors, fans, etc.).
• Water tight base.

Sometimes it turns out a sale isn't really a sale

I use egg crate lighting diffuser trimmed to fit in the water trays for my other orchids.  Turns out that this, plus some PVC pipe as spacers, is a standard solution for lifting plants above the water line in vivariums.  After dumping a couple inches of water into the base and closing the doors, I'm getting humidity in the mid 70s, which is a big improvement.

Next up is getting an arduino doing some monitoring of the environment inside the case.