"SD_SCK in use" when trying to use SD SPI on Metro RP2350

[todbot]

CircuitPython version and board name

Adafruit CircuitPython 10.0.0-beta.0 on 2025-07-15; Adafruit Metro RP2350 with rp2350b

Code/REPL

import os, time, board, busio, sdcardio
try_adafruit_sdcard = True
mount_point = "/sd"

# pin definitions
sd_sck   = board.SD_SCK   # board.GP34   # "CLK"
sd_mosi  = board.SD_MOSI  # board.GP35   # "SI"
sd_miso  = board.SD_MISO  # board.GP36   # "SO"
sd_cs    = board.SD_CS    # board.GP39   # "CS"

# sd card setup
if try_adafruit_sdcard:
    print("trying adafruit_sdcard")
    import adafruit_sdcard, digitalio
    sd_spi = busio.SPI(clock=sd_sck, MOSI=sd_mosi, MISO=sd_miso)
    cs = digitalio.DigitalInOut(sd_cs)
    sdcard = adafruit_sdcard.SDCard(sd_spi, cs)
else:
    print("trying sdcardio")
    sd_spi = busio.SPI(clock=sd_sck, MOSI=sd_mosi, MISO=sd_miso)
    sdcard = sdcardio.SDCard(sd_spi, sd_cs)
vfs = storage.VfsFat(sdcard)
storage.mount(vfs, mount_point)
while True:
    for filename in os.listdir(mount_point):
        print("filename:",filename)
    time.sleep(0.5)

Behavior

code.py output:
trying adafruit_sdcard
Traceback (most recent call last):
  File "code.py", line 15, in <module>
ValueError: SD_SCK in use

Description

There seems to be no way to release the SD SPI pins being used.
Trying to do a minimal version of the SD Card Read Test in the Learn Guide results in "SD_SCK in use" error.

Additional information

No response

[dhalbert]

This is because we've now added automounting in recent 10.0.0 builds for SD cards when a board has an SD card detect pin, which this board does.

If you don't bother to try to mount the card explicitly, you'll discover that os.listdir("/sd") will list the files on the board. In addition the card is visible as a drive on the host computer.

Note this issue: #10510.

[todbot]

Oof. Okay so the Learn Guide needs to be updated a lot then 😀. It also means we can't do performance tests between adafruit_sdcard, sdcardio and sdioio. I assume it's using sdcardio under the hood? Is there a way to know?

[dhalbert]

Yes, we have to document this, and yes, it uses sdcardio. You can do storage.umount("/sd") to unmount, and then mount again however you wish.

@tannewt can say more as well.

[todbot]

If I wanted to unconfigure all the auto-configured stuff on the Metro RP2350, so far I know to do:

displayio.release_displays()
storage.umount("/sd")
usb_host.???

Is there a method to unconfigure the PIO-USB usb host stuff?

[tannewt]

Is there a method to unconfigure the PIO-USB usb host stuff?

Nope. TinyUSB doesn't have a way to deinit.