Server Room Environmental Monitoring -Light and Temperature

April 27, 2011 by · 6 Comments
Filed under: Arduino, Projects 

Did I leave the light on in the server room again? Kind of like “did I leave the oven on”… its going to bug me all night!
At least I am well on my way to answering that, and several other questions I might be wondering.

My goal with this project is to set up a remote monitoring device I can place in my server room that will display basic information such as temperature, ambient light values, decibels, current draw, etc.

Right now I have a 16×2 character LCD from JKdevices. Its compatible with the Hitachi HD44780, so it works great with the Arduino LiquidCrystal library. I have it connected in 4bit mode.

Arduino with potentiometer, temperature and light sensors


I have the arduino reading the 3 sensors and storing them to variables. the light and potentiometer values are stored to an integer, and the temperature is stored in a float. Those variables are then “printed” to the LCD screen, every 500 milliseconds.

Here is the temperature sensor  (based around Ti’s TMP421), which I purchased from Liquidware. the breakout board is manufactured  by Modern Devices.  It’s accurate to within +/- 1 degree Celsius, or for us Americans, +/- 1.8 degrees Fahrenheit. It’s based off the I2C protocol, and includes a library to  make things (somewhat) easier to use.

Modern Devices I2C Temp Sensor


The light sensor is the same sensor I used in my 555 contest submission. It is manufactured by Vishay. The TEMT6000 [datasheet] from Sparkfun Electronics . Right now I have no idea what units i am reading, just that the value changes proportionally to the amount of light.

The final item on the display is displaying the value from a potentiometer. Not much use for that unless I need a position sensor for something that rotates or opens.

I’m ordering a few more sensors – more to come as parts come in!


LCD Pinout

Blue Backlit LCD
Standard HD44780 Interface
Runs on 5 volts
16×2 Character Display
4 Mounting Holes
pin    symbol    description
1    GND    Ground
2    Vcc    Vcc (+5V) also powers backlight
3    V0    Contrast adjustment
4    RS    Register select: low = instruction, high = data
5    R/W    low = write, high = read
6    E    Enable (active high)
7    DB0    Data-bus bit 0 (not used in 4-bit mode)
8    DB1    Data-bus bit 1 (not used in 4-bit mode)
9    DB2    Data-bus bit 2 (not used in 4-bit mode)
10    DB3    Data-bus bit 3 (not used in 4-bit mode)
11    DB4    Data-bus bit 4
12    DB5    Data-bus bit 5
13    DB6    Data-bus bit 6
14    DB7    Data-bus bit 7
15    LED+    Positive backlight supply (if used)
16    LED-    Negative backlight supply (if used)


Update 5/13/2011

PIR sensor and Audio level sensor have arrived, along with ethernet shield. Trying to get something solid together over the weekend, before next week’s Maker Faire in SF.


Update 6/14/2011

Received new parts – sparkfun i2C  backpack for LCD.
Ran into a snag with my Arduino duemilanove -i think i blew up burned out the FTDI chip! Not to worry, I hooked up the Xbee for easy “wireless” programming! Got the backpack soldered to the LCD and got it displaying temperatures. Biggest issue was finding the right code to talk to an i2c display, then pushing over the temperature data. The temperature from the sensor is stored as a Float. Floats will not transfer over the serLCD from Sparkfun, so I needed to change it to an integer first. Who knew?



Charliplexed Led E-textile Patch

April 15, 2011 by · Leave a Comment
Filed under: Electronics, Projects 

Did you bring a hack? – (Spring of 2011 -Pre Maker Faire SF Bay Area)

Answering this question was the driving motivation in getting this project underway. After seeing several Charlieplex links on hack-a-day, I decided it was high time that I give it a try myself. I wanted something I didn’t have to carry around, so a T-shirt seemed like a logical choice. I had seen some other LED based e-textiles, but didn’t want to use huge 3mm or 5mm LED’s. Surface Mount Led’s came to mind, but I was not sure how to go about soldering anything to conductive thread.

Fortunately, I ran across an article describing how to mount surface mount LEDs to fabric by way of soldering small crimp beads to each end. This provided a place to loop the conductive thread through the LED.

First, acquire crimp beads and leds:

Seccond: Assemble

Each SMT led has a silver ring attached to it.

Next I had to decide how to design and control the Charlieplex.

The first step, was a prototype circuit and layout. I really have to thank this guy [Ben] for posting helpfull information on the web. His 5×4 Charliplex display walkthrough provided me with the design I used to lay out the e-textile. I ended up taking his hand drawn schematic and using it as my t-shirt layout with minimal changes. I don’t have a printer at home, so I actually traced this schematic from a sheet of paper I placed over my monitor, and transferred that to the front and back of the fabric.

Then I added the conductive thread and components.


then I cut out a square, attached some connectors and an Arduino, and stuck it to a shirt!