Accelerometer readings based on switch setting , stops prematurely

[Kesse79]

I have written the following code for the Raspberry Pico which in core0 will run accelerometer readings. Based on a switch state connected to the Pico, the accelerometer readings will light a red LED if specific treshold values are exceeded.
Core1 will run a fan from 0-100 % and back to 0 % again.

The script works fine when the switch_state == 0 , but setting the switch_state == 1 causes the script to only take one accelerometer reading and then terminating the script as the example below

0.02770996 0.04833984 0.9343262
Exiting core0_thread

Can anyone help me explain why switch_state == 1 does not react similar to switch_state == 1 ?

Code is copied in below.

Any help I can get is highly appreciated :-)

Kind regards
Christen

`from machine import Pin, PWM 
import _thread
from mpu6050 import MPU6050
import time

# Global variable to signal the threads to exit
exit_threads = False

def core0_thread():
    global exit_threads

    led_red = Pin(12, Pin.OUT)   # Red LED
    led_green = Pin(13, Pin.OUT) # Green LED
    mpu = MPU6050(1, 15, 14) # bus(1), SCL(GP15), SDA(GP14)

    switch = Pin(8, Pin.IN, Pin.PULL_UP)  # Assuming the switch is connected to GPIO 8

    while True:
        try:
            mpu.MPU_Init() # initialize the MPU6050
            time.sleep(1)  # wait for MPU6050 to work steadily
              
            accel = mpu.MPU_Get_Accelerometer() # gain the values of Acceleration
            
            # Calculate the acceleration values in floating-point format
            accelx = accel[0] / 16384.0
            accely = accel[1] / 16384.0
            accelz = accel[2] / 16384.0

            # Read the state of the switch
            switch_state = switch.value()
            
            # Show the calculated values in Thonny's plotter
            print(accelx, accely, accelz)
            
            if switch_state == 0:  # Switch activated (closed)
                
                if -0.30 < accelx < 0.30 and -0.30 < accely < 0.30 and 0.70 < accelz < 1.30:
                    led_red.off() # Turn off the red LED
                    led_green.on() # Turn on the green LED
                else:
                    led_green.off() # Turn off the green LED
                    led_red.on() # Turn on the red LED
                    
                    break
                
            if switch_state == 1:  # Switch open
                
                if -1.30 < accelx < 1.30 and -1.30 < accely < 1.30 and 1.70 < accelz < 2.30:
                    led_red.off() # Turn off the red LED
                    led_green.on() # Turn on the green LED
                else:
                    led_green.off() # Turn off the green LED
                    led_red.on() # Turn on the red LED
                    
                    break

            time.sleep(0.1)
                
        except Exception as e:
            print(e)
            time.sleep(1) # wait for 1 second before retrying the loop
            
    print("Exiting core0_thread")

def core1_thread():
    global exit_threads

    led_red = Pin(12, Pin.OUT)   # Red LED
    fanpwm = PWM(Pin(6))
    fanpwm.freq(1000)

    while not exit_threads:
        for duty in range(0, 65535, 1):
            if led_red.value() == 1: # check if the red LED is on
                fanpwm.duty_u16(0) # set fan speed to 0%
                break
            fanpwm.duty_u16(duty)
            time.sleep(0.001)

        for duty in range(65535, 0, -1):
            if led_red.value() == 1: # check if the red LED is on
                fanpwm.duty_u16(0) # set fan speed to 0%
                break
            fanpwm.duty_u16(duty)
            time.sleep(0.001)

        # Signal the threads to exit after one full cycle of fan pwm i.e. from 0 to 100 % and then back to 0 %
        exit_threads = True

    print("Exiting core1_thread")

# Start the second thread
second_thread = _thread.start_new_thread(core1_thread, ())

# Start the first thread in the main thread
core0_thread()

`

[davefes]

Why do the limits change for accel values in the test for switch_state == 1?

After if switch_state == 1: print out the accel values

[peterhinch]

I would suggest that in state 1 the condition 1.70 < accelz < 2.30 is not being met, causing the break instruction to be executed. The loop will then quit.

Incidentally initialising the MPU in a loop is unnecessary. Do it once before the start of the loop.

[Kesse79]

Thank you very much for your suggestions. I really appreciated the fast response to my question.
@peterhinch you were absolutely right. The code was actually working, however the fan tested in state 1 had vibrations greater than the treshold values in reading no. 2 and therefore ended the script as intended after only one accelerometer reading. I have now increased the treshold values and see that everything runs fine.

Have a wonderful day !