Memorial piece for a friend's pet groundhog. Because what's more groundhog than predicting the weather every groundhog day?
Uses an Adafruit Feather M0 and RTC FeatherWing to maintain time. Common clock drive mechanisms have current requirements for the second hand coil that are within the pin drive capability of an M0, and so the battery and quartz oscillator were bypassed to allow direct ticking of the second hand under software control. On being plugged in, the clock runs at double-speed until magnets mounted to the hour and minute hands are detected to establish hand position. From that point onwards, the second hand of the clock is driven up to 2x slow or fast, proportionally to the error between the RTC and the measured position of the minute hand as it passes the sensor every hour, resulting in convergence to the true time within a day. An OLED FeatherWing provides a user interface to allow for setting time zones.
A Teensy 3 is used to control stepper motors for the Day/Date/Month wheels, with target positions transmitted via serial. Each wheel has a hall effect zero-position sensor to calibrate on startup.
Winnie predicts how long until spring at 7am every Groundhog Day.
Body laser-cut at Ponoko, printed parts SLS from Shapeways. My one improvement if I did this again would be custom PCBs to remove all of the wires.
Uses an Adafruit Feather M0 and RTC FeatherWing to maintain time. Common clock drive mechanisms have current requirements for the second hand coil that are within the pin drive capability of an M0, and so the battery and quartz oscillator were bypassed to allow direct ticking of the second hand under software control. On being plugged in, the clock runs at double-speed until magnets mounted to the hour and minute hands are detected to establish hand position. From that point onwards, the second hand of the clock is driven up to 2x slow or fast, proportionally to the error between the RTC and the measured position of the minute hand as it passes the sensor every hour, resulting in convergence to the true time within a day. An OLED FeatherWing provides a user interface to allow for setting time zones.
A Teensy 3 is used to control stepper motors for the Day/Date/Month wheels, with target positions transmitted via serial. Each wheel has a hall effect zero-position sensor to calibrate on startup.
Winnie predicts how long until spring at 7am every Groundhog Day.
Body laser-cut at Ponoko, printed parts SLS from Shapeways. My one improvement if I did this again would be custom PCBs to remove all of the wires.
