112 lines
2.9 KiB
Python
112 lines
2.9 KiB
Python
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"""
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Skytracker by Nick Touran for ESP8266 and Stepper Motors
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Port by Jon Saul <jonsaul@puppetmaster.lol>
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This accelerates the motor to correct the tangent error. It can rewind too!
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Motors are 28BYJ-48 5V + ULN2003 Driver Board from Amazon
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Hook up power and ground and then hook inputs 1-4 up to GPIO pins.
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See Also: http://www.raspberrypi-spy.co.uk/2012/07/stepper-motor-control-in-python/
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This motor has a 1:64 gear reduction ratio and a stride angle of 5.625 deg (1/64th of a circle).
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So it takes 64*64 = 4096 single steps for one full rotation, or 2048 double-steps.
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with 3 ms timing, double-stepping can do a full rotation in 2048*0.003 = 6.144 seconds
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so that's a whopping 1/6.144 * 60 = 9.75 RPM. But it has way more torque than I expected.
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Can get 2ms timing going with double stepping on ESP8266. Pretty fast!
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Should power it off of external 5V.
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Shaft diameter is 5mm with a 3mm inner key thing. Mounting holes are 35mm apart. """
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from machine import Pin
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from machine import Timer
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import math
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import time
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NUM_PINS = 4
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NUM_STEPS = 8
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RADS_PER_SEC = 7.292115e-05
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LENGTH_CM = 28.884 # fill in with precise measured value
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# For theta zero, I used relative measurement between two boards w/ level.
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# Got 0.72 degrees, which is 0.012566 radians
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THETAO = 0.012566
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ROTATIONS_PER_CM = 7.8740157
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DOUBLESTEPS_PER_ROTATION = 2048.0
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CYCLES_PER_SECOND = 80000000
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# Modes
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NORMAL = 0
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REWINDING = 1
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STOPPED = 2
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motorPins = [
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Pin(16, Pin.out), # D0
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Pin(5, Pin.out), # D1
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Pin(4, Pin.out), #D2
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Pin(14, Pin.out) #D5
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]
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MODE_PIN = Pin(13, Pin.out) #D7
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STEPPER_SEQUENCE = [
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[1,0,0,1],
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[1,0,0,0],
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[1,1,0,0],
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[0,1,0,0],
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[0,1,1,0],
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[0,0,1,0],
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[0,0,1,1],
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[0,0,0,1]
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]
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step_delta = 0
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step_num = 0
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total_seconds = 0.0
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totalsteps = 0
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step_interval_s = 0.001
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current_step = 0
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next = 0
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now = 0
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last_toggle = 0
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current_mode = NORMAL
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autostop = True
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def ypt(ts):
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# Bolt insertion rate in cm/s: y'(t)
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# Note, if you run this for ~359 minutes, it goes to infinity!!
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return LENGTH_CM * RADS_PER_SEC/math.pow(math.cos(THETAO + RADS_PER_SEC * ts),2)
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def step_motor():
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"""
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This is the callback function that gets called when te timer
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expires. It moves the motor, updates lists, recomputes
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the step interval based on the current tangent error,
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and sets a new timer.
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"""
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pass
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def do_step(current_step):
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# apply a single step of the stepper motor on its pins.
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pass
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def setup():
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pass
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def setup_timer():
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pass
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def setup_gpio():
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for i in NUM_PINS:
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Pin(motorPins[i], Pin.OUT)
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all_pins_off()
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button = Pin(MODE_PIN, Pin.IN)
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button.irq(trigger=Pin.IRQ_FALLING, handler=toggle_mode)
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pass
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def all_pins_off():
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for i in NUM_PINS:
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Pin(motorPins[i], Pin.low())
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def toggle_mode():
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# We have several modes that we can toggle between with a button,
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# NORMAL, REWIND, and STOPPED.
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pass
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def loop():
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pass
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