Designing and building an automatic cat feeder


The littleBits module chain was simply p3 USB Power -> Cloud bit -> Split Wire -> two Servomotors (Figure 7). Next, I wrote IFTTT (If This Then That) recipes that triggered the servos at certain times of the day (Figure 8).

Figure 7: The littleBits chain (left to right): Power, Cloud, Split Wire, Servomotors.
Figure 8: The IFTTT recipe says that if it's 1:15pm, activate the RLSBit, which is the name of my Cloud module. Once the Cloud bit is activated, it sends a signal down the chain, which in this case, comprises the two servos. Similar recipes were written for other feeding times.

The tubs slots matched up when the servo arm rotated. For this project, the servo was set to Turn mode, rather than Swing mode. I connected a littleBits Button to the servos temporarily to calibrate the position of the containers so that the slots matched up at the maximum rotation of the servomotor arm.

Practical Considerations

The automatic feeder delivered food reliably, but the kibble scattered when it hit the bowls, so I made two paper chutes to guide the food gently into the bowls (Figure 9). The cats were very interested in the feeder when I first set it up, but after it activated, they were wary of re-approaching it. However, after the mechanism had remained quiet for a while, they approached and ate as usual. The cats had to change the way they normally ate to keep from hitting their heads on the tubs, though, so a future design change would be to raise the height of the tubs.

Figure 9: The automatic pet feeder from the front showing the paper food guides.

One difficulty I encountered was aligning the inner tub with the outer tub, so I took a straightened paper clip and put it in the servo hub to guide the inner tub into the correct position (Figure 10). Speaking of tubs, on my next attempt at making a pet feeder, I will make sure to use containers that do not hold strong-smelling food. The clam chowder tub worked well, but I was never able to get rid of the odor from the chicken tortilla soup tub.

Figure 10: A guide wire helped position the inner tub in the outer tub.

The electronics hung over the back of the bracket and were secured with wire ties (Figure 11). Ultimately, the littleBits should be protected from dust, water, and cat fur in some sort of container.

Figure 11: The electronics hung over the back of the bracket. The green light on the Cloud bit means the module is communicating on the home wireless network.

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