Espressif 20Mhz operation breaks usb operation till next reset

adafruit / circuitpython

CircuitPython - a Python implementation for teaching coding with microcontrollers

https://circuitpython.org

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Espressif 20Mhz operation breaks usb operation till next reset #9536

Open bill88t opened 3 months ago

bill88t commented 3 months ago

CircuitPython version

Any > #9342, discovered on S3

Code/REPL

import microcontroller
microcontroller.cpu.frequency = 20_000_000 # 20MHz

Behavior

Usb goes away. This is fine as by itself, as usb cannot operate with the board being at 20MHz. However when switched back to a higher clock, usb does not start back up, even if the board is unplugged and plugged back in (assuming it's battery powered).

bill88t commented 2 months ago

This does not happen if the USB filesystem is disabled from boot.py. In other words, USB reconnects when just USB-CDC is enabled.