COLLECTING REALTIME DATA FROM ARDUINO
The below shows historic and realtime data collected from an Arduino MEGA with a DHT22 sensor and a light sensor. Data is logged once per second from the Arduino to a mysql database and Apex Charts are used to display the data. If you would like more information on this project including the build, you can find a full run down of it here. The timer is currently set to update the data every five seconds but this is configurable depending on requirements.
The above dial shows a "real time" reading from a DHT22 sensor. The frequency of the data pushing and pulling is configurable in the scripts and will dependent on the application. This app receives data from the arduino once per second and the dial refreshes also once per second.
The chart above shows the average humidity over time and is updated every two hours, again this can be altered as you need but for this chart it is not particularly time critical so to ease any database load a period of two hours is applied.
Using a light sensor on an analog pin of the arduino we can record data in realtime to our database, above we show an example of how to plot hourly readings for the day in real time to a web page.
All time humidity levels in a room plotted out in "real time" with data from the DHT22 humidity sensor. Data is averaged over an hour to smooth out any bumps caused by windows opening and so on. Worth noting that these sensors are very cheap and I will be comparing the readings on these sensors to try and ascertain the accuracy and repeatablility of them in a future project.