Vibration tester - maintain LEDs on during cycle

[Kesse79]

Hi everyone,

I am working on a vibration test device based on a raspberry Pico and a MCU6050 accellerometer. The following code works well - but i am having difficulties solving how to maintain the LED status on, if this status is set once during the PWM cycle. Can any of you clever people help me sort this out ?

The code is copied in below

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
    led_yellow = Pin(11, Pin.OUT)
    led_blue = Pin(10, Pin.OUT)
    mpu = MPU6050(1, 15, 14) # bus(1), SCL(GP15), SDA(GP14)
    
    # Turn off all LEDs
    led_red.off()
    led_green.off()
    led_yellow.off()
    led_blue.off()    
    

    

    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


            
            
            # Show the calculated values in Thonny's plotter
            print(accelx, accely, accelz)
            


                
            if -1.30 < accelx < 1.30 and -1.30 < accely < 1.30 and 1.00 < accelz < 2.30:

                led_blue.off() 
            else:
                led_blue.on()
                

            if -2.30 < accelx < 2.30 and -2.30 < accely < 2.30 and 0.00 < accelz < 3.30:

                led_green.off() # Turn off the green LED
            else:
                led_green.on()               

            if -3.30 < accelx < 3.30 and -3.30 < accely < 3.30 and -1.00 < accelz < 4.30:

                led_yellow.off() # Turn off the yellow LED
            else:
                led_yellow.on

            if -4.30 < accelx < 4.30 and -4.30 < accely < 4.30 and -2.00 < accelz < 5.30:

                led_red.off() # Turn off the red LED 
            else:
                led_yellow.on
                
            time.sleep(0.05)
                
        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()

[peterhinch]

I am not entirely sure what the problem is, but I did note that there is no code to turn the red LED on.

[Kesse79]

Hi Peter,

Thanks - great observation. I will change the red led on function, in the next version of the code :-)

Basically the core1thread will control a fan that runs from 0 to 100 % and then back to 0 % again (a full cycle). During the fancycle the core0thread is monitoring if the vibrations from the fan exceed the treshold values. When the vibrations from the fan exceed the treshold values accelx,y,z the LED will light up.
My problem is that once the LED light up due to the treshold values beeing exceeded - the infinite while loop will turn the LED off again during the next loop. I would like to maintain the LED on for the complete fan cycle if the LED has been turned on.

[peterhinch]

Why not code it so that, at the start of the cycle all the LEDs are turned off. During the cycle, LED's can only be turned on, as in this fragment:

            if not (-3.30 < accelx < 3.30 and -3.30 < accely < 3.30 and -1.00 < accelz < 4.30):
                led_yellow.on()
            if not (-4.30 < accelx < 4.30 and -4.30 < accely < 4.30 and -2.00 < accelz < 5.30):
                led_red.on()

[Kesse79]

Hi Peter,

You are absolutely right - this should work. Thank you very much for your help and great advice.

Kind regards
Christen