Port, board and/or hardware

Pico

MicroPython version

MicroPython v1.30.0-preview.58.g14e9793c91 on 2026-09-04; Raspberry Pi Pico with RP2040

Reproduction

import time
from machine import mem32
import _thread

def thread_entry(a, b):
    try:
        core_num = mem32[0xd0000000]
    except Exception as e:
        print(f'function thread entry exception {e}')
    print(f'core {core_num} thread {_thread.get_ident()} {a} {b}')

# spawn thread using kw args
id = _thread.start_new_thread(thread_entry, (10, 20))
core_num = mem32[0xd0000000]
print(f'core {core_num} thread {_thread.get_ident()}')

time.sleep(1)

Expected behaviour

Expected no exception. See different behavior based on the order of execution.

Observed behaviour

core 0 thread 1
function thread entry exception name 'mem32' isn't defined
Unhandled exception in thread started by <function thread_entry at 0x20007250>
Traceback (most recent call last):
File "", line 13, in thread_entry
NameError: local variable referenced before assignment

Additional Information

In the code posted above, in the function 'thread_entry' changing mem32 to machine.mem32 resolves the issue.
Alternately, moving 'core_num = mem32[0xd0000000]' to before starting the thread resolves the issue.

Code of Conduct

Yes, I agree