Python Forum

Wierd problem been trying to resolve for several hours - appreciate any help !

I'm runinng an ADC-sampler in a separate thread function, which logs the max-sample found during each second (approx).

It signals 'main' that the max-value is ready via a flag global.... while also posting the max-value in a data global.

Below is the code and the output. 'main' gets signaled properly via the flag global, but the data-value doesn't arrive - it's usually 0, but about 20% of the time some odd non-0 value.

import machine
import _thread

################################################
# Variables
global readyFlag	
readyFlag = False

global max_found
max_found = 0

################################################
# Functions

def sampler_thread(): 		# Function that will be launched as a separate thread.
    global readyFlag
    global max_found
    
    adc1 = machine.ADC(26)            # Start an ADC
    while True: 
        max_found = 0                 # Init to smallest possible value before sampling-loop

        cnt = 20000                   # Init loop-cntr
        while cnt > 0:                # Loop until counter=0
            cnt -= 1
            sample = adc1.read_u16()  # Get next sample
            if sample > max_found:    # If >max-found, set it to max-found
                max_found = sample

        print("sampler max_found:", max_found)
        readyFlag = True              # Tell the 'main' thread that max_found is ready.

##############################################
# Main 
_thread.start_new_thread(sampler_thread, ())

while True:
    if readyFlag:
        print("main max_found:",max_found)
        readyFlag = False

**********************
OUTPUT SAMPLE ('sampler max_found' is correct, but 'main' gets mostly 0's or odd#):
sampler max_found: 2688
main max_found: 2368

sampler max_found: 2704
main max_found: 0

sampler max_found: 2672
main max_found: 0

sampler max_found: 2688
main max_found: 2128

What is the target os? Why aren't you using the threading module?