36 lines
919 B
Python
36 lines
919 B
Python
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import time
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import math
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from breakout_ioexpander import BreakoutIOExpander
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ioe_servo_pin = 1
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# Settings to produce a 50Hz output from the 24MHz clock.
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# 24,000,000 Hz / 8 = 3,000,000 Hz
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# 3,000,000 Hz / 60,000 Period = 50 Hz
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divider = 8
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period = 60000
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cycle_time = 5.0
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servo_range = 1000.0 # Between 1000 and 2000us (1-2ms)
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ioe = BreakoutIOExpander(0x18)
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ioe.set_pwm_period(period)
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ioe.set_pwm_control(divider)
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ioe.set_mode(ioe_servo_pin, BreakoutIOExpander.PIN_PWM)
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t = 0
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while True:
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s = math.sin((t * math.pi * 2.0) / cycle_time) / 2.0
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servo_us = 1500.0 + (s * servo_range)
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duty_per_microsecond = period / (20 * 1000) # Default is 3 LSB per microsecond
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duty_cycle = round(servo_us * duty_per_microsecond)
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print("Cycle Time: ", t % cycle_time, ", Pulse: ", servo_us, ", Duty Cycle: ", duty_cycle, sep="")
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ioe.output(ioe_servo_pin, duty_cycle)
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time.sleep(0.02)
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t += 0.02
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