Taste The Rainbow One Color At A Time

It’s the end of another fall semester of Bruce Land’s ECE4760 class at Cornell, and that means a fresh crop of microcontroller-based student projects. For their project, [Alice, Jesse, and Mikhail] built a Skittle-sorting miniature factory that bags and seals same-colored candies into little pouches of flavor.

Their design is split into three stages, which are visually delineated within the all-cardboard housing. Skittles are loaded into a funnel at the top that leads to the color detection module. The color is determined here with an RGB LED and OPT101 photodiode driven by an ATMega1284.  Because the reflected RGB values of red and orange Skittles are so similar, the detector uses white light to make the final determination.

Once the matchmaking is over, a servo in the second stage rotates to the angle that corresponds with the color outcome. The Skittle then slides down a cardboard chute, passes through a hole in a cardboard disk, and drops into a hanging bag. Once the bags have reached the predetermined capacity, another servo moves the carousel of bags to a nichrome wire sealing rig. Lead factory worker [Jesse] must intervene at this point to pull the bags off the line. You can see the full walk-through and demonstration of this Skittle flavor separator after the break.

13 thoughts on “Taste The Rainbow One Color At A Time

      1. “We initially powered the circuit directly from a voltage source, however, this has the potential to draw too much current from the supply. In order to limit supply current draw, we changed our circuit to discharge from a capacitor and added a current limiting resistor on the supply. An 8900 �F capacitor powers our servo when the solenoid is grounded. The capacitor is connected to the 12V supply line and a T=14mS. We are not operating the solenoid faster than .5Hz, which makes this time constant sufficient to fully charge the capacitor. “

  1. A great project – now if the students knew just how much work goes into getting the individual colors mixed more-or-less homogeneously for final packaging in the candy factory….

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