John's Vademecum

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====== Watchwinder  ======

==== Home Brew Winder ====

I built a simple watch-winder to keep automatic watches fully wound when not being worn. Mainly as a small project to play with a [[https://store.micropython.org/product/PYBv1.1H|pyBoard]] and a servo motor.

A short piece of microPython makes the servo turn, first one direction, then then other, then a pause, at a speed that makes sure a watch is fully wound overnight. The speed depends on the required number of turns to achieve full-wind, which depends on the watch movement, and whether the movement winds in one or other, or both, rotational directions.

The watch is placed in a plastic box attached to the servo motor and the motor is simple clamped in a ''panavise'', with the axis of the servo at about 45°

==== Photos ====

<WRAP col2>

[[https://docs.micropython.org/en/latest/pyboard/quickref.html|pyBoard Quick Reference]]

{{:public:watches:pyboard.jpg?300|}}

{{:public:watches:pybv11-pinout.jpg?300|}}


{{:public:watches:winder_1.jpg?300|}}

{{:public:watches:winder_2.jpg?300|}}

{{:public:watches:winder_3.jpg?300|}}

{{:public:watches:winder_4.jpg?300|}}

</WRAP>

<todo #john:2025-03-09>add some photos</todo>


==== Python Code ====

microPython  code for Pyboard to control continuous rotation servo.

<code python>

# main.py -- put your code here!


import pyb

servo1 = pyb.Servo(1)

# LED colours
# red flash = motor stopped
# green on = manual stop for 120 seconds
# yellow on/flash = motor running
# blue flash = 5 seconds before a change of state

ledr = pyb.LED(1) 
ledg = pyb.LED(2)
ledy = pyb.LED(3)
ledb = pyb.LED(4) 

# servo speeds to achieve approx 6 rpm in either direction.
ccw = 14
cw = -7
stop = 0


# 12 minute cycle :
# observed turns complete per stage:
# 2 min CW = ~11 turns
# 4 min stop
# 2 min CCW = ~ 12 turns
# 4 min stop
# 23 turns / 12 min = 115 turns / hour
# ETA 2836-2 requires 650 turns / day for full winding 
# this would take 5.6 hours on winder per day to guarantee full wind.

period = 120 # seconds

# turn LEDs off (unneccesary?)
ledr.off()
ledg.off() 
ledy.off()
ledb.off()

# interrupt function to allow changing/removing watch
def stop_servo():
	
	# red LED on at start of interruption
	ledr.on()
	ledy.off()
	
	# turn off any flashing LEDs during interruption
	tim4.callback(None)
	
	# flash blue LED to signal stop imminent
	flash_blue()
	
	# stop servo
	servo1.speed(0)
	
	# red LED off and green LED on to indicate "safe to proceed"
	ledr.off()
	ledg.on()
	
	# pause for 2 minute
	pyb.delay(120 * 1000)
	
	# flash blue LED to signal re-start imminent
	flash_blue()
	
	# green LED off to indicate end of interruption.
	ledg.off()

	pyb.hard_reset()
	
	# after resumption from interrupt the next stage will usually be a 
	# "stop" period, assuming the interrupt occurred during a "run" period
	# perhaps need to look at the best way of resuming? or even quit()
	# at the end of the stop_servo() interrupt and then manually reset via the 
	# RST button?
	
	# main programme resumes where it left off....
	return
	
def cycle_led():
	
	ledb.on()
	pyb.delay(500)
	ledy.on()
	pyb.delay(500)
	ledg.on()
	pyb.delay(500)
	ledr.on()
	pyb.delay(500)
	ledb.off()
	ledy.off()
	ledg.off()
	ledr.off()
	
	return
	
def flash_blue():
	
	t = 0
	while t < 10:
		 
		ledb.toggle()
		pyb.delay(500)
		t += 1
	return

def rotate_cw(p):
	
	# solid yellow LED when going CW
	ledy.on()
	servo1.speed(cw, 1000)
	pyb.delay(p * 1000)
	flash_blue()
	ledy.off()
	
	return
	

def rotate_ccw(p):

	# flash yellow LED when going CCW
	tim4.callback(lambda t: ledy.toggle())
	servo1.speed(ccw, 1000)
	pyb.delay(p * 1000)
	flash_blue()
	tim4.callback(None)
	ledy.off()

	
	return
	
	
def pause(p):

	# flash red LED during motor pause period
	tim4.callback(lambda t: ledr.toggle())
	servo1.speed(stop, 1000)
	pyb.delay(p * 1000)
	flash_blue()
	tim4.callback(None)
	ledr.off()
	
	return
	

# USR on-board switch used to pause running to allow
# watch to be removed / changed
sw = pyb.Switch()

# callback to run the function that pauses the operation
sw.callback(stop_servo)
	
#timer to flash LEDs
tim4 = pyb.Timer(4, freq=2)

cycle_led()

# the main loop
while True:
		
		rotate_cw(period)
		
		pause(2 * period)
			
		rotate_ccw(period)
	
		pause(2 * period)
		

</code>


==== Page Info ====

Page created Sun May 22 00:52:45 2022 by John Pumford-Green

Page last updated: ~~LASTMOD~~

{{tag>watch python}}