QUERY · ISSUE
RP2 hangs when using I2S and bitstream
bugport-rp2
Port, board and/or hardware
rp2
MicroPython version
MicroPython v1.25.0 on 2025-04-15; Raspberry Pi Pico with RP2040
Reproduction
Running the following code in Thonny.
I have run it on an official Pico 2 W, and an RP2040-zero board from AliExpress.
I have run it on stock firmware (1.25.0), the stock ulab firmware (based on 1.24.0), and my own build (1.26.0-preview + ulab).
I have run it with both the external peripherals attached (8x8 WS2812B matrix and an INMP441 clone from AliExpress), and nothing attached to the board other than USB power.
All exhibit the same problem.
import machine, sys
from machine import Pin, I2S
from neopixel import NeoPixel
MTX_DIN = const(14)
MIC_ID = const(0)
MIC_SCK = const(6)
MIC_WS = const(7)
MIC_SD = const(8)
SAMPLE_RATE = const(22050) # Hz
SAMPLE_BITS = const(16)
SAMPLE_COUNT = const(512)
if sys.platform == 'rp2':
assert MIC_WS == MIC_SCK + 1
mtx = NeoPixel(Pin(MTX_DIN), 64)
raw = bytearray(SAMPLE_COUNT * SAMPLE_BITS // 8)
mic = None
try:
mic = I2S(MIC_ID,
sck=Pin(MIC_SCK), ws=Pin(MIC_WS), sd=Pin(MIC_SD),
rate=SAMPLE_RATE, bits=SAMPLE_BITS,
mode=I2S.RX, format=I2S.MONO,
ibuf=len(raw)*2)
loop = 0
while True:
print(loop, 'loop begins')
num_bytes_read = mic.readinto(raw)
assert (num_bytes_read == len(raw))
print(loop, 'microphone read')
mtx.write() # hangs
# machine.bitstream(mtx.pin, 0, mtx.timing, mtx.buf) # hangs, equivalent to mtx.write()
# machine.bitstream(mtx.pin, 0, mtx.timing, mtx.buf[:144]) # hangs
# machine.bitstream(mtx.pin, 0, mtx.timing, mtx.buf[:72]) # usually works
print(loop, 'bitstream() done')
loop = loop + 1
print('next', loop)
except Exception as e:
sys.print_exception(e)
finally:
try: mic.deinit()
except: pass
Expected behaviour
The loop runs indefinitely.
Observed behaviour
0 loop begins
0 microphone read
0 bitstream() done
next 1
(and nothing else, it doesn't actually start the next loop, and the device must be power-cycled)
If I replace mtx.write() with one of the alternatives, it either hangs (for larger numbers of bytes) or runs fine (smaller number of bytes).
Additional Information
Slightly different versions of the code were sometimes printing unexpected strings instead of "next" (for example "enable_irq" and "bin")
Code of Conduct
Yes, I agree
CANDIDATE · ISSUE
rp2: No Pin IRQ on core 1 (on core 0: OK)
bugport-rp2
Port, board and/or hardware
RP2, PICO and PICO2, RP2040 and RP2350
MicroPython version
MicroPython v1.26.0 on 2025-08-09; Raspberry Pi Pico2 with RP2350
No Pin() IRQ when using the second core (_thread).
Primary core works as intended.
Reproduction
#!micropython
# -*- coding: UTF-8 -*-
# vim:fileencoding=UTF-8:ts=4
#╭──────────────────────────────────────────────────────────────────────────────╮
#│ PICO_THREAD_PIN_IRQ_TEST.PY │
#│ Board: PICO2/RP2350 │
#│ Micropython: 3.4.0; MicroPython v1.26.0 on 2025-08-09 │
#│ Testing: Pin.irq() on both cores │
#│ using a bridge between GPIO16 and GPIO17 │
#│ GPIO16 runs a slow PWM │
#│ GPIO17 acts as an input with IRQ │
#╰──────────────────────────────────────────────────────────────────────────────╯
import _thread
from sys import version
from array import array
from machine import Pin, PWM
from time import sleep_ms
_SIO_BASE = const(0xd0000000)
_CPUID = const(0x000 >>2)
_THREAD_HLT = const(0)
_THREAD_RUN = const(1)
_THREAD_FIN = const(2)
@micropython.viper
def cpuid() -> int:
sio: ptr32 = ptr32(_SIO_BASE)
return sio[_CPUID]
def core1(data,hard):
def cb_core1(pin):
print('cb_core1(): IRQ on core:', cpuid(), end=' ')
print('count:', data[1])
if data[1]:
data[1] -= 1
print('core1() is running on core:', cpuid())
pin = Pin(17, Pin.IN, Pin.PULL_UP)
data[1] = 5
pin.irq(handler=cb_core1, trigger=Pin.IRQ_FALLING, hard=hard)
while data[0] == _THREAD_RUN and data[1]:
sleep_ms(10)
pin.irq(None)
pin.init()
data[0] = _THREAD_FIN
return
def core0():
def cb_core0(pin):
print('cb_core0(): IRQ on core:', cpuid(), end=' ')
print('count:', data[1])
if data[1]:
data[1] -= 1
print(version)
data = array('I', (_THREAD_HLT,0)) # [0]state [1] counter
pwm = PWM(16, freq=10, duty_u16=2**15)
print('Testing hard=False on core 0')
pin = Pin(17, Pin.IN, None)
data[1] = 5
pin.irq(handler=cb_core0, trigger=Pin.IRQ_FALLING, hard=False)
while data[1]:
sleep_ms(10)
pin.irq(None)
pin.init()
print('Testing hard=True on core 0')
pin = Pin(17, Pin.IN, None)
data[1] = 5
pin.irq(handler=cb_core0, trigger=Pin.IRQ_FALLING, hard=True)
while data[1]:
sleep_ms(10)
pin.irq(None)
pin.init()
print('Testing hard=False on core 1')
data[0] = _THREAD_RUN
_thread.start_new_thread(core1, (data,False))
loops = 100
while (loops:= loops-1) and data[0] != _THREAD_FIN:
sleep_ms(10)
data[0] = _THREAD_HLT
while data[0] != _THREAD_FIN: pass
print('Testing hard=True on core 1')
data[0] = _THREAD_RUN
_thread.start_new_thread(core1, (data,True))
loops = 100
while (loops:= loops-1) and data[0] != _THREAD_FIN:
sleep_ms(10)
data[0] = _THREAD_HLT
while data[0] != _THREAD_FIN: pass
pwm.deinit()
core0()
3.4.0; MicroPython v1.26.0 on 2025-08-09
Testing hard=False on core 0
cb_core0(): IRQ on core: 0 count: 5
cb_core0(): IRQ on core: 0 count: 4
cb_core0(): IRQ on core: 0 count: 3
cb_core0(): IRQ on core: 0 count: 2
cb_core0(): IRQ on core: 0 count: 1
Testing hard=True on core 0
cb_core0(): IRQ on core: 0 count: 5
cb_core0(): IRQ on core: 0 count: 4
cb_core0(): IRQ on core: 0 count: 3
cb_core0(): IRQ on core: 0 count: 2
cb_core0(): IRQ on core: 0 count: 1
Testing hard=False on core 1
core1() is running on core: 1
Testing hard=True on core 1
core1() is running on core: 1
### Expected behaviour
Well, should fire IRQ/callback events when running on core 1.
### Observed behaviour
Does not.
### Additional Information
No, I've provided everything above.
### Code of Conduct
Yes, I agree