initial

.gitignore

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+/venv
+/.servo-state
+/.idea

README.md

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+# opi-mg996r
+
+This is a Python implementation of MG996R servo support for Orange Pi boards (H3 specifically, others untested).
+It does not use hardware PWM but instead emulates PWM with primitive `time.sleep()` calls, so don't expect any real-time 
+accuracy. And, well, it's Python, after all.
+
+But it does its job and MG996R servo works just fine!
+
+## Usage
+
+- Clone the repo.
+- Install dependencies (see [here](requirements.txt)).
+- Check out [example.py](example.py) for an example.
+
+You can also just use it from command line like this:
+```
+./example.py --deg 0
+./example.py --deg 180
+./example.py --deg 90
+```
+
+## Credits
+
+The softpwm implementation was taken the [orangepwm](https://github.com/evergreen-it-dev/orangepwm) project.
+
+## License
+
+MIT

example.py

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+#!/usr/bin/env python3
+import os, logging
+from argparse import ArgumentParser
+from mg996r import MG996R
+
+default_degree = 360
+state_file = '.servo-state'
+
+if __name__ == '__main__':
+    # set logging level
+    logging.basicConfig(level=logging.DEBUG)
+
+    # parse arguments
+    parser = ArgumentParser()
+    parser.add_argument('--deg', type=int, required=True)
+    parser.add_argument('--pin', type=str, default='PA6',
+                        help='GPIO pin to use')
+    parser.add_argument('--reset', action='store_true',
+                        help=f'Use clean default state (degree = {default_degree})')
+    args = parser.parse_args()
+
+    start_degree = default_degree
+
+    # restore previous degree from a file
+    if not args.reset:
+        try:
+            if os.path.exists(state_file):
+                with open(state_file, 'r') as f:
+                    start_degree = int(f.read())
+                    if not 0 <= start_degree <= 360:
+                        raise ValueError(f'invalid degree value in {state_file}')
+        except (IOError, ValueError) as e:
+            logging.exception(e)
+            start_degree = default_degree
+
+    servo = MG996R(args.pin, start_degree)
+    servo.move(args.deg)
+
+    # save degree to a file
+    try:
+        with open(state_file, 'w') as f:
+            f.write(str(args.deg))
+    except IOError as e:
+        logging.exception(e)

mg996r.py

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+import logging
+
+from time import sleep
+from orangepwm import OrangePwm
+from pyA20.gpio import gpio
+from pyA20.gpio import port
+
+
+class MG996R:
+    def __init__(self, pin: str, prev: int = 360):
+        self.pwm = OrangePwm(50, getattr(port, pin))
+        self.prev = prev
+        gpio.init()
+
+        logging.debug(f'Initialized MG996R class with starting degree of {prev}')
+
+    def move(self, deg, delay: int = 0):
+        distance = abs(self.prev - deg)
+        sleep_time = distance / 60 * .5 + delay
+
+        duty = deg / 18 + 2
+        logging.debug(f'Moving to {deg} degrees, duty {duty:.0f}%, sleeping for {sleep_time:.1f} sec.')
+
+        self.prev = deg
+
+        self.pwm.start(duty)
+        sleep(sleep_time + delay)
+        self.pwm.stop()

orangepwm.py

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+from pyA20.gpio import gpio as GPIO
+import threading
+import time
+
+
+class OrangePwm(threading.Thread):
+    def __init__(self, frequency, gpioPin, gpioScheme=0):
+        """
+        Init the OrangePwm instance. Expected parameters are :
+        - frequency : the frequency in Hz for the PWM pattern. A correct value may be 100.
+        - gpioPin : the gpio.port which will act as PWM ouput
+        - gpioScheme : saved for compatibility with PiZyPWM code
+        """
+        super().__init__()
+
+        self.baseTime = 1.0 / frequency
+        self.maxCycle = 100.0
+        self.sliceTime = self.baseTime / self.maxCycle
+        self.gpioPin = gpioPin
+        self.terminated = False
+        self.toTerminate = False
+        # GPIO.setmode(gpioScheme)
+
+    def start(self, dutyCycle):
+        """
+        Start PWM output. Expected parameter is :
+        - dutyCycle : percentage of a single pattern to set HIGH output on the GPIO pin
+
+        Example : with a frequency of 1 Hz, and a duty cycle set to 25, GPIO pin will
+        stay HIGH for 1*(25/100) seconds on HIGH output, and 1*(75/100) seconds on LOW output.
+        """
+        self.dutyCycle = dutyCycle
+        GPIO.setcfg(self.gpioPin, GPIO.OUTPUT)
+        self.thread = threading.Thread(None, self.run, None, (), {})
+        self.thread.start()
+
+    def run(self):
+        """
+        Run the PWM pattern into a background thread. This function should not be called outside of this class.
+        """
+        while self.toTerminate == False:
+            if self.dutyCycle > 0:
+                GPIO.output(self.gpioPin, GPIO.HIGH)
+                time.sleep(self.dutyCycle * self.sliceTime)
+
+            if self.dutyCycle < self.maxCycle:
+                GPIO.output(self.gpioPin, GPIO.LOW)
+                time.sleep((self.maxCycle - self.dutyCycle) * self.sliceTime)
+
+        self.terminated = True
+
+    def changeDutyCycle(self, dutyCycle):
+        """
+        Change the duration of HIGH output of the pattern. Expected parameter is :
+        - dutyCycle : percentage of a single pattern to set HIGH output on the GPIO pin
+
+        Example : with a frequency of 1 Hz, and a duty cycle set to 25, GPIO pin will
+        stay HIGH for 1*(25/100) seconds on HIGH output, and 1*(75/100) seconds on LOW output.
+        """
+        self.dutyCycle = dutyCycle
+
+    def changeFrequency(self, frequency):
+        """
+        Change the frequency of the PWM pattern. Expected parameter is :
+        - frequency : the frequency in Hz for the PWM pattern. A correct value may be 100.
+
+        Example : with a frequency of 1 Hz, and a duty cycle set to 25, GPIO pin will
+        stay HIGH for 1*(25/100) seconds on HIGH output, and 1*(75/100) seconds on LOW output.
+        """
+        self.baseTime = 1.0 / frequency
+        self.sliceTime = self.baseTime / self.maxCycle
+
+    def stop(self):
+        """
+        Stops PWM output.
+        """
+        self.toTerminate = True
+        while self.terminated == False:
+            # Just wait
+            time.sleep(0.01)
+
+        GPIO.output(self.gpioPin, GPIO.LOW)
+        GPIO.setcfg(self.gpioPin, GPIO.INPUT)

requirements.txt

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+git+git://github.com/duxingkei33/orangepi_PC_gpio_pyH3@master