non_blocking_hw_api.py

import time

class RangeSensor:

    def __init__(self):
        pass

    def make_generator(self):
        t_end = time.time() + 0.1
        # tell sensor to start measurement
        while time.time() < t_end:       # while it isn't done yet
            yield None                   # yield None
        # read the result from the sensor
        yield 'result'

    def range(self):
        # the blocking call creates a generator and waits until it stops
        local_generator = self.make_generator()
        while True:
            try:
                val = next(local_generator)
            except StopIteration:
                break
            if val is not None:
                return val

    def range_non_blocking(self):
        # the non blocking call creates a generator if necessary and returns its current value
        # when no new value is available, it can either return None or the previous value
        try:
            val = next(self.range_generator)
        except AttributeError:
            self.range_generator = self.make_generator()
            val = next(self.range_generator)
        except StopIteration:
            self.range_generator = self.make_generator()
            val = next(self.range_generator)
        return val

class Accel:
    def x(self):
        return(1)

rs = RangeSensor()
accel = Accel()

# example 1
tw_end = time.time() + 0.3
while time.time() < tw_end:
    val = rs.range_non_blocking()
    if val is None:
        print('...', end='\r')
    else:
        print(val)

# example 2
tw_end = time.time() + 0.3
while time.time() < tw_end:
    print(accel.x(), rs.range_non_blocking())
    time.sleep(0.025)

This idea for non blocking sensor reads allows for fast data logging of multiple sensors without having to deal with each sensors specific delay and without the need of an event loop.