QUERY · ISSUE

rp2: rp2.asm_pio_encode incorrectly accepts 'pins' as src for 'wait'

openby ccanepaopened 2022-09-15updated 2026-03-19

bugport-rp2

https://docs.micropython.org/en/latest/library/rp2.html#module-rp2 specifies the pio asm syntax for 'wait' as
wait(polarity, src, index) where 'src' one of (gpio, pin, irq)
The rp2040-datasheet.pdf similary uses (GPIO, PIN, IRQ)

The bug is that rp2.asm_pio_encode silently accepts the invalid src value 'pins'. It should raise an exception.

Incidentaly it encodes "wait(1, pins, 0)" the same as "wait(1, gpio, 0)"

demo code

import rp2
try:
    rp2.asm_pio_encode("wait(1, pins, 0)")
    exception_raised = False
except Exception:
    exception_raised = True

assert exception_raised

CANDIDATE · ISSUE

RP2350: PIO2 State Machines do not work

closedby IntergalacticMicrosystemsopened 2025-06-17updated 2025-08-01

bugport-rp2

Port, board and/or hardware

ports-rp2 Pico 2

MicroPython version

MicroPython v1.26.0-preview.251.g5ade8b705 on 2025-06-16; Raspberry Pi Pico2 with RP2350

Reproduction

pio_1hz.py from examples does not blink the LED or trigger the interrupt when switched to StateMachine IDs 8, 9, 10, or 11.

Expected behaviour

No response

Observed behaviour

What I've found so far:
PIO2_BASE + SM0_EXECCTRL is set incorrectly
PIO2 instruction memory is not loaded
Instruction start address is not set

Additional Information

This code mostly works.
The IRQ handler only triggers once, not repeatedly as expected.

import time
from machine import Pin
import rp2

@rp2.asm_pio(set_init=rp2.PIO.OUT_LOW)
def blink_1hz():
    # fmt: off
    # Cycles: 1 + 1 + 6 + 32 * (30 + 1) = 1000
    irq(rel(0))
    set(pins, 1)
    set(x, 31)                  [5]
    label("delay_high")
    nop()                       [29]
    jmp(x_dec, "delay_high")

    # Cycles: 1 + 1 + 6 + 32 * (30 + 1) = 1000
    nop()
    set(pins, 0)
    set(x, 31)                  [5]
    label("delay_low")
    nop()                       [29]
    jmp(x_dec, "delay_low")
    # fmt: on


# Create the StateMachine with the blink_1hz program, outputting on Pin(25).
sm = rp2.StateMachine(8, blink_1hz, freq=2300, set_base=Pin(25))

# Set the IRQ handler to print the millisecond timestamp.
sm.irq(lambda p: print(time.ticks_ms()))

# -------- MANUAL REGISTER SETTING START -----------
import machine
PIO2_BASE = 0x50400000
SM0_EXECCTRL = 0xCC
INSTR_MEM0 = 0x48
SM0_INSTR = 0xD8
machine.mem32[PIO2_BASE + SM0_EXECCTRL] = 129920
instrs = [49168, 57345, 58687, 48450, 89, 41026, 57344, 58687, 48450, 94]
instr_start = 0x48 + (4 * (32-len(instrs)))
for idx,instr in enumerate(instrs):    
    machine.mem32[PIO2_BASE + instr_start + (idx*4)] = instr
machine.mem32[PIO2_BASE + SM0_INSTR]=32-len(instrs)
# -------- MANUAL REGISTER SETTING END -----------

# Start the StateMachine.
sm.active(1)

while(True):
    pass

Code of Conduct

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