Fish Feeder Project

thingiverse

Update Dec 19 2017 marks the first anniversary of operation with no major modifications required since then. This project is a remake of "Automatic Fish Feeder with Micro Servo Control V2" by Paulo Cunha. I made some minor adjustments to certain parts, redesigned the hopper and added a base part as well as a control box. Initially, I used the original design that included a mixer inside the hopper powered by a spur gear. However, this sometimes led to flake food getting jammed in the hopper, and the mixer did not effectively prevent such situations from occurring. To solve this problem, I removed the horizontal mixer and added a much larger vertical mixer powered by an additional servo motor. After two months of operation, it appears that this new design is quite reliable. Video: https://youtu.be/azTHyCNVLFo The electronics are based on the ATTiny841 chip programmed in the Arduino IDE. My main goal was to keep power consumption low. The CPU spends most of its time in sleep mode, and there is no display. Operation is triggered by a real-time clock module DS3231. Powered by a single 18650 Li-ion rechargeable battery. I chose the ATTiny841 because it features an integrated hardware serial interface. I use this for setting time, alarms, etc. I did not use an Arduino Mini or any other option because I had to create a PCB board for other components anyway, so I included the CPU there. By other components, I mean n-channel mosfet switches mainly. Two 9G servo motors are used – modified to work as DC motors (removed electronics and connected directly to motor, cracked potentiometer to allow free rotation) Features: • precise real-time clock • two independent programmable alarms (feeds) in a day • programmable via serial link • adjustable time duration for auger and mixer servo (separately) • button for instant feed (out of alarm time) • buttons for adjusting feed servo run duration • indication of low battery voltage Electronics: The electronics are quite simple – ATTiny 841 controls servo motors via two n-channel mosfet switches. RTC board and Li-ion charger board are available on eBay: RTC DS3231: http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR0.TRC0.H0.XIIC+Precision+RTC+Real+Time+Clock+Memory+Module++DS3231+AT24C32.TRS0&_nkw=IIC+Precision+RTC+Real+Time+Clock+Memory+Module++DS3231+AT24C32&_sacat=0 CHARGER: http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR0.TRC0.H0.XMini+USB+Lithium+Battery+Charging+Board.TRS0&_nkw=Mini+USB+Lithium+Battery+Charging+Board&_sacat=0 Detailed description is included in the attached PDF file. Source Arduino, Eagle, Inventor files are also attached.