Raspberry Pi Pico - Soft reset doesn't clear out pin usage state

[dannystaple]

Firmware

Adafruit CircuitPython 6.2.0 on 2021-04-05; Raspberry Pi Pico with rp2040

Adafruit CircuitPython 6.2.0-beta.2 on 2021-03-01; Raspberry Pi Pico with rp2040

Code/REPL

import board
import displayio
import busio
from adafruit_st7789 import ST7789

spi = busio.SPI(board.GP18, MOSI=board.GP19)
while not spi.try_lock():
    pass
spi.configure(baudrate=24000000) # Configure SPI for 24MHz
spi.unlock()
tft_cs = board.GP17
tft_dc = board.GP16

displayio.release_displays()
display_bus = displayio.FourWire(spi, chip_select=tft_cs, command=tft_dc)

display = ST7789(display_bus, width=240, height=240, rowstart=80, rotation=180)

print("Hello on the display!")

Behavior

It runs the first time, but if I make changes and save (causing soft reset) or Ctrl-D for a soft reset, I get the following:

code.py output:
Traceback (most recent call last):
  File "code.py", line 5, in <module>
ValueError: GP18 in use

Description

Only seen so far with this SPI setup - but this is my first CircuitPython/Pico SPI device usage.

• might be related to SAMD51 - Soft reset doesnt clear out pin usage state #352...

[tannewt]

Displays hold onto their pins so that they live through the reset. You'll want a displayio.release_displays() before you reconstruct it.

[tannewt]

More specifically, you'll want it before you reconstruct the SPI.

[dannystaple]

Thanks. It's a shame I can't use atexit for this. I'm thinking mini-game code that potentially has a big while loop, and I'm assuming the soft exit doesn't come through as an exception that I could handle with a finally clause. Are there any good patterns for that?

[tannewt]

Thanks. It's a shame I can't use atexit for this. I'm thinking mini-game code that potentially has a big while loop, and I'm assuming the soft exit doesn't come through as an exception that I could handle with a finally clause. Are there any good patterns for that?

The MicroPython merge brought in atexit functionality but they lumped it into sys so I disabled it. It shouldn't be too hard to move and enable.

You may be interested in #3454 which was done with game code in mind too. It has mechanics for what to do after an exception.