Current stepper for EDF

currentstep.py

import time, serial
from datetime import datetime

ser = serial.Serial('COM17')
time.sleep(10)
path = datetime.now().strftime('%Y-%m-%d-%H%M%S') + ".log"
file = open(path, 'w')
ser.write(b'S')
counter = 5
forwards = True

# `attrs` is the distribution package name...
try:
    import attrs # learn more: https://python.org/pypi/attrs
except ModuleNotFoundError:
    pass

# but the python package name you import is `attr`
import attr


@attr.s
class PeriodicTime:
    period = attr.ib()
    clock = attr.ib(default=time.monotonic)
    now = attr.ib()
    last = attr.ib()
    avoid_drift = attr.ib(default=True)
    
    @now.default
    def _(self):
        return self.clock()
    
    @last.default
    def _(self):
        return self.now

    def due(self):
        self.now = self.clock()
        elapsed = self.now - self.last
        due = elapsed >= self.period
        
        if due:
            if self.avoid_drift:
                self.last += self.period
            else:
                self.last = self.now
        
        return due
    
    def set_last(self, last=None):
        if last is None:
            self.last = self.clock()
        else:
            self.last = last


periodic_time = PeriodicTime(period=5)

while 1:
    data = ser.readline().decode('utf-8').strip()
    time_string = str(time.time())
    print(data + ',' + time_string)
    file.write(data + ',' + time_string + "\n")
    if periodic_time.due():
        if(forwards):
            if(counter == 50):
                forwards = False
                ser.write(b'-')
                counter -= 5
            elif(counter < 50):
                ser.write(b'+')
                counter += 5
        elif(forwards == 0):
            if(counter == 0):
                ser.write(b's')
                break
            ser.write(b'-')
            counter -= 5
        
ser.close()