Deprecated: Function set_magic_quotes_runtime() is deprecated in /home/dfmoore/ on line 14
Notes: Mold Tracker: Notes



Mold Tracker: Notes

Jan 22, 11:27 AM

Temperature & Humidity Sensor

About this project

I think I may have some leaks in my apartment walls. I occasionally hear drips splashing down. I’d like to insert a sensor into my walls and measure how much humidity is kicking around, since mold needs water to grow. Appreciable levels of humidity will be a good indicator that something is wrong.

Since most of the Arduino community relies on website resources, I’m going to document my sunday afternoon project. I’ll be using the RHT03 sensor, available on SparkFun. I’ll be reporting data back to a MySQL database, and then using Processing to graph the data over time.

Background Information

Sensor Description
Arduino Library

Pinout looking directly at the part:
(1) (2) (3) (4)
Vdd Data Null Gnd

NB: Vdd and Vcc both mean the positive supply voltage. The naming convention comes from the type of IC or part it’s powering; VCC typically labeled for BJT’s, and VDD for FETs. What does this mean? It’s the + pin for your power supply, and GND is the -.

Supply part with 3.3v ->6v DC. It’s okay to connect to the 5v pin on your arduino.

We’ll be using a digital pin on the arduino that we can access with interrupts: Pin 7.
Connect a 4.7kohm resistor between VDD and the data pin. This is a pullup resistor and helps eliminate spurious ‘floating input’ data.

This pin gets no connection. Just leave it be.

Connect up to your arduino’s ground pin.


1. Getting data with the Arduino
2. Sending data to the computer
3. MySQL database queries
4. Graphing the data with Processing