Barn door tracker - control system
The stepper motor on the barn door tacker is controlled by the Arduino microcontroller, right. The Arduino interfaces with the stepper motor through the A4988 Stepper Motor Carrier Driver on the breadboard, left. The microswitch is the 'home' sensor that is mounted on the hinge.
On power-on and reset, the control system opens and closes the hinge while monitoring the state of the home-sensing switch to locate the home position, when the actuator is extended at nominal zero millimeters. Thereafter, the controller extends the actuator to open the hinge to match the earth's rotation. (The resistor on the Arduino isn't part of the circuit. I'm using its lead to access the Arduino's Pin 8 ditital output.)
Missing from this circuit are:
- The kill switch that will shut off the motor if the software
looses its mind.
- The circuitry to microstep. As shown, the stepper motor
resolution is 1/200th of a turn per step instead of the
intended 1/3200th of a turn per microstep.
- The 12 Volt battery pack that powers the control system and the stepper motor.
- The DC-DC converter that steps down 12V power to 5V
required by the control system.
I might expand the Arduino's functionality to implement an anti-dew system, too. I have a 12V supply that can deliver plenty of current. Perhaps I'll implement an adjustable PWM output on the Arduino to drive a transitor that will control a heater for the camera lens. It doesn't take much energy to drive off the dew.
Barn door tracker - control system
The stepper motor on the barn door tacker is controlled by the Arduino microcontroller, right. The Arduino interfaces with the stepper motor through the A4988 Stepper Motor Carrier Driver on the breadboard, left. The microswitch is the 'home' sensor that is mounted on the hinge.
On power-on and reset, the control system opens and closes the hinge while monitoring the state of the home-sensing switch to locate the home position, when the actuator is extended at nominal zero millimeters. Thereafter, the controller extends the actuator to open the hinge to match the earth's rotation. (The resistor on the Arduino isn't part of the circuit. I'm using its lead to access the Arduino's Pin 8 ditital output.)
Missing from this circuit are:
- The kill switch that will shut off the motor if the software
looses its mind.
- The circuitry to microstep. As shown, the stepper motor
resolution is 1/200th of a turn per step instead of the
intended 1/3200th of a turn per microstep.
- The 12 Volt battery pack that powers the control system and the stepper motor.
- The DC-DC converter that steps down 12V power to 5V
required by the control system.
I might expand the Arduino's functionality to implement an anti-dew system, too. I have a 12V supply that can deliver plenty of current. Perhaps I'll implement an adjustable PWM output on the Arduino to drive a transitor that will control a heater for the camera lens. It doesn't take much energy to drive off the dew.