RP2: ADC pins does not work properly in XIAO RP2350
Port, board and/or hardware
XIAO RP2350
MicroPython version
MicroPython v1.26.1 on 2025-09-11; Seeed XIAO RP2350 with RP2350
Reproduction
- Use the firmware in this interface XIAO_RP2350
- Use the following test code
import machine
machine.ADC(29).read_u16()
Expected behaviour
Using my own compiled firmware
MicroPython v1.27.0-preview.135.gd28844d11b.dirty on 2025-09-15; Seeed XIAO RP2350 with RP2350
Type "help()" for more information.
>>> import machine
>>> machine.ADC(4).read_u16()
13955
Observed behaviour
MicroPython v1.26.1 on 2025-09-11; Seeed XIAO RP2350 with RP2350
Type "help()" for more information.
>>> import machine
>>> machine.ADC(29).read_u16()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: Pin doesn't have ADC capabilities
>>>
Additional Information
The reason is that pico-sdk is not the latest.
The ADC function modified the judgment logic after this submission, and changed the range of the ADC pin to be specified by macro(ADC_BASE_PIN and NUM_ADC_CHANNELS).
See: https://github.com/micropython/micropython/commit/34e463d861c5ebb33ec317749a008d461616cfbc
These two macros were not used in pico-sdk until after this commit.
See: https://github.com/raspberrypi/pico-sdk/commit/c88bd53a68fe2199fa4a5e6473ba88278f339a2b
The following file is the xiao rp2350 header file in the pico-sdk used by the current version of micropython. This file does not include the changes submitted above.
See: https://github.com/raspberrypi/pico-sdk/blob/9a4113fbbae65ee82d8cd6537963bc3d3b14bcca/src/boards/include/boards/seeed_xiao_rp2350.h
Please update pico-sdk and release a new firmware version as soon as possible.
Code of Conduct
Yes, I agree
RP2350: PIO scripts fail, despite running on RP2040
Port, board and/or hardware
Pico 2
MicroPython version
MicroPython v1.25.0-preview.408.gf315a376b on 2025-03-26; Raspberry Pi Pico2 with RP2350
Reproduction
It has proved hard to produce a minimum repro, what follows is my best shot. The repro is quite fragile - minimal changes cause its behaviour to vary between working and failing.
Link GPIO numbers 1-18 and 2-17 and run the following:
import rp2
from machine import Pin, SPI
@rp2.asm_pio(autopush=True, autopull=True)
def spi_count():
out(x, 32)
wait(0, pins, 2) # CS/ True
label("loop")
jmp(pin, "good")
jmp(x_dec, "loop")
label("good")
in_(x, 32)
label("finish")
jmp("finish")
class Test:
def __init__(self, start_pin=0, sm_num=0):
self._sm1 = rp2.StateMachine(
sm_num,
spi_count,
in_base=start_pin,
jmp_pin=start_pin + 1,
)
self._sm1.active(1)
def go(self, cs, ck):
sm = self._sm1
sm.put(10_000_000)
cs(0) # Start
ck(1) # Stop
assert sm.rx_fifo(), "Rx fifo is empty."
print(sm.get())
cs = Pin(17, Pin.OUT, value=1)
ck = Pin(18, Pin.OUT, value=0)
t = Test()
t.go(cs, ck)
Expected behaviour
Result on RP2040 is to print a number around 9999759.
Observed behaviour
RP2350 produces an assertion fail. I assume that the RP2350 is failing to respond to the jump pin.
Additional Information
No, I've provided everything above.
Code of Conduct
Yes, I agree