Googly eyed Minion clock by KiwiGrinder

Last crawled date: 3 years ago

This remake adds new software and hardware to gwfong's Googly Eyes Minion Clock remake (https://www.instructables.com/id/Googly-Eyes-Minion-Clock/) based on Minion Dave by Poh (https://www.thingiverse.com/thing:403110).
I have created a PCB that holds a ULN2803A octal darlington transistor array to drive the two stepper motors. It also contains a DS1302 real time clock chip, its crystal and battery. It is driven by an Arduino Pro Mini. The Eagle files are included. I used the toner method to create the board.
The software supports two buttons.
The MIDNIGHT button is used to tell the software where the 12 O'clock position is. You can rotate the eyes with your fingers and press this button when the eyeballs are in the correct location.
The MODE button switches between clock mode and one of four random animations.
The RTC needs to be set via the Arduino IDE Serial Monitor when the FTDI programmer is present. Just sent the date and time in the form yyyy,MM,dd,hh,mm,ss and the software will program the RTC.
I sourced my parts from eBay and they are all easily obtainable. I got the DS1302, crystal and battery holder from a cheap RTC board (https://www.ebay.com/itm/DS1302-Clock-Module-Real-Time-Clock-Module-for-arduino-without-Battery-CA-NEW/141976854631?hash=item210e7ae067:g:B60AAOxyDo1TjwO9). The only 25mm stepper motors I could find were from eBay (https://www.ebay.com/itm/1pcs-For-NMB-DC5V-15-25mm-4-Phase-5-Wire-Step-Stepping-Stepper-Motor-With-Gear/231225110024?hash=item35d6172e08:g:T4UAAOxyThVTabLK).
These motors are fragile and have very poor resolution. They have 24 steps per revolution making the minute hand move 2.5 minutes on each step. Also, because they have no gearing, they don't have much torque. The software can accommodate higher resolution stepper motors. If anyone ever does modify this design to use 28BYJ-48 stepper motors for example, you can change the defines at the start of the code. You may need to reduce the RPM speed for higher resolution stepper motors.
PS: If any of you design experts do redesign this to take 28BYJ-48 stepper motors, my suggestion to you would be to mount them near the back and put the eyeballs on long shafts.