May-29-2019, 06:14 AM
I don't know why you can't do it with threading. Here is my code. It reads the sensor every second and warns if the threshold is reached. It also prints a temperature report every 5 seconds (python 3.5 code). It also does all this while waiting for user input to exit gracefully and potentially do other actions.
import datetime as dt
import random
import sys
from threading import Thread, Event
monitor_event = Event()
PROMPT = 'Type quit to quit: '
def print_msg(msg):
print()
print(msg)
print(PROMPT, end='')
sys.stdout.flush()
def read_temperature():
temp = random.gauss(30, 7)
# print('reading', temp)
return temp
class Monitor(Thread):
def __init__(self, delta_sensor, delta_report, threshold):
Thread.__init__(self)
self.ds = delta_sensor.total_seconds()
self.delta_report = delta_report
self.threshold = threshold
def run(self):
# self.resume = True
self.next_report = dt.datetime.now() + self.delta_report
while True:
monitor_event.clear()
monitor_event.wait(timeout=self.ds)
if monitor_event.is_set():
break
temp = read_temperature()
if temp > self.threshold:
print_msg(
'Warning: temperature {:.1f} above threshold {:.1f}'.format(
temp, self.threshold))
t = dt.datetime.now()
if t >= self.next_report:
print_msg(
'{:%Y-%m-%d %H:%M:%S}: current temperature is {:.1f}'.format(
t, temp))
self.next_report = t + self.delta_report
if __name__ == "__main__":
monitor = Monitor(dt.timedelta(seconds=1), dt.timedelta(seconds=5), 40)
monitor.start()
try:
while True:
s = input(PROMPT)
if s.strip().lower() in ('q', 'quit'):
break
finally:
monitor_event.set()
monitor.join()Output:λ python3 paillasse/cooler.py
Type quit to quit:
2019-05-29 08:12:04: current temperature is 27.4
Type quit to quit:
2019-05-29 08:12:09: current temperature is 36.9
Type quit to quit:
2019-05-29 08:12:14: current temperature is 25.2
Type quit to quit:
2019-05-29 08:12:19: current temperature is 25.3
Type quit to quit:
2019-05-29 08:12:24: current temperature is 28.4
Type quit to quit:
2019-05-29 08:12:29: current temperature is 34.4
Type quit to quit:
2019-05-29 08:12:34: current temperature is 26.3
Type quit to quit:
Warning: temperature 46.6 above threshold 40.0
Type quit to quit:
Warning: temperature 41.8 above threshold 40.0
Type quit to quit:
2019-05-29 08:12:39: current temperature is 29.3
Type quit to quit:
2019-05-29 08:12:44: current temperature is 31.3
Type quit to quit:
Warning: temperature 42.2 above threshold 40.0
Type quit to quit: quit