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Larry Ogrodnek, creator of the LED NameTag kit, figured out a great way to use an RGB backlight LCD to display temperature data.

This is a really simple ambient display for temperature using an Arduino, an RGB backlight LCD, and a temperature sensor.

The LCD displays the temperature in Fahrenheit and Celsius and adjusts the color of the backlight depending on the reading. An ideal range is set at 61F to 67F. If the temperature is in this range the backlight will change green. Above this range and the color will change red, below the range it will change blue.

The great thing about these kinds of displays is that you can immediately get some rough information from across the room.

This is just a quick project. An obvious improvement is to have more variations in color depending on how far you are from your ideal range. I.e. as the temperature increases out of the ideal range, move along the color wheel and use shades of yellow, then orange before hitting red. There’s also a lot of empty room on that LCD. Possibly room for data from other sensors, or maybe just a larger (2-line) font.

This is perfect for someone like me who only needs 5 different temperature increments; really cold, cold, nice, hot, and really hot. Most of these parts and (Larry’s NameTag kit) are available in the Maker Shed.

[via Analog Machines]

Michael Castor

Michael Castor

I am the Evangelist for the Maker Shed. It seems that there is no limit to my making interests. I’m a tinkerer at heart and have a passion for solving problems and figuring out how things work. When not working for Make I can be found falling off my unicycle, running in adverse weather conditions, skiing down the nearest hill, restoring vintage motorcycles, or working on my car.


  • davidcdean

    Except that I don’t have the rgb backlight in my serial lcd, this was one of my very first projects with an arduino board.

    It was encouraging for a noob like me to get some useful information back about the physical world. It solidifies the idea that you can do practical things, not just blink a light.

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  • Peter in Ithaca

    It would be nice to see this for commercial kitchen refrigerators along with a data log of temps. They make them now but they are pricey. Ideally, you’d want something that emails you a daily summary of temp variations.

  • Gregg

    where can I find more details and the code?

  • patricio1976

    A small experimentation i made: