If else statement not behaving correctly

Question

I am using a Raspberry Pi Pico-W with MicroPython to build a small temperature alarm. I have tried to build in some hysteresis however the output is using the upper value not the lower one.

I.e. in the code below alarm 1 switches on at 31 but off again at 30.8

from machine import Pin, I2C
import utime as time
from dth import DHT11, InvalidChecksum, InvalidPulseCount
pin = Pin(16, Pin.OUT, Pin.PULL_DOWN)
sensor1 = DHT11(pin)

pwr = Pin(22,Pin.OUT, Pin.PULL_DOWN)
alarm1 = Pin(21,Pin.OUT, Pin.PULL_DOWN)
alarm2 = Pin(20,Pin.OUT, Pin.PULL_DOWN)

alarm1temp = 30
alarm1hum = 60

alarm2temp = 35
alarm2hum = 80

temphys = 1
humhys = 2

temp = 0
hum = 0
retrys = 5
pwr.on()
while True:
    time.sleep(2)
    retrycounter = 0
    while retrycounter <= retrys:
        try:
            new_temp = sensor1.temperature
            new_hum = sensor1.humidity
            temp = new_temp
            hum = new_hum
            break
        except:
            print("Error reading data. Try: "+str(retrycounter))
            time.sleep(1)
            if retrycounter > retrys-1:
                    temp = alarm2temp + 1
            retrycounter += 1
            
            
    print("Temperature: {}".format(temp))
    print("Humidity: {}".format(hum))
    
    if temp >= (alarm1temp+temphys) or hum >= (alarm1hum+humhys):
        alarm1.on()
        print("Alarm 1 On")
    elif temp < alarm1temp or hum < alarm1hum:
        alarm1.off()
        print("Alarm 1 Off")
        
    if temp >= (alarm2temp+temphys) or hum >= (alarm2hum+humhys):
        alarm2.on()
        print("Alarm 2 On")
    elif temp < alarm2temp or hum < alarm2hum:
        alarm2.off()
        print("Alarm 2 Off")

Answer 1

I assume that the humidity is below the alarm threshold, so this section will reset alarm1, as soon as the temperature drops below alarm1temp+temphys (and therefore the initial if is false)

elif temp < alarm1temp or hum < alarm1hum:
    alarm1.off()
    print("Alarm 1 Off")

Changing the or to and should fix it.

TL;DR: You need either thing to be true to set the alarm, but both to be false to clear it.