I’ve finally made some time to work on the temperature monitor for the server room.
The Temperature Monitor currently consists of an Arduino Uno R3, Ethernet Shield and a small prototyping board.
It will currently listen to port 80 on an internal IP address. When a request comes in it will create a simple web page that shows the raw value from the sensor, degrees Kelvin, degrees Celsius and degrees Fahrenheit. In addition to the web page there is an RGB LED that reflects the current temperature. The picture below shows the simple web page and the color scale for the RGB LED.
The prototype board consists of the two sections:
LM335A temperature sensor, 2K ohm resistor and a 10k ohm potentiometer.
The LM335 has a positive terminal, negative (signal) terminal and an adjustment terminal. The 10k pot attaches to the adjustment terminal to help calibrate the LM335A.
3 x 220 ohm resistors and an RGB LED.
The RGB LED is driven by three PWM outputs from the Arduino which controls the effective voltage sent to each of the Red, Green and Blue terminals on the LED.
The LED will be solid blue when the temperature is 65 degrees or colder, solid green at 73 degrees, solid yellow at 81 degrees and solid red at 89 degrees or greater. This provides an at-a-glance status of the temperature in the server room.
After I get the Arduino sketch cleaned up a little I’ll post the first draft of the program.
– Better looking web page. Pulled from an SD card on the Ethernet Shield. Will use character replacement to ‘inject’ the variables into the web page.
– The formula for calculating the temperature is dependent on the current voltage entering the system. Would like to be able to measure the operating voltage and feed that value back into the formula for calculating the temperature.
– Add averaging into the ‘current’ temperature to filter stabilize the LED and values on the web page