nrf52840: add USBVBusPresent to detect USB cable unplug via SoftDevice#462
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nrf52840: add USBVBusPresent to detect USB cable unplug via SoftDevice#462sago35 wants to merge 1 commit into
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The POWER peripheral is restricted while the SoftDevice is enabled, so USB VBUS presence must be read through sd_power_usbregstatus_get instead of machine's own USB detection. This matters because TinyGo's machine layer never notices the cable being unplugged (the USB power SOC events are drained unhandled by this package's event pump), so on a battery-powered device with a serial monitor attached, machine.Serial.Write blocks forever once its TX ring fills up after unplug. Callers can guard debug output with this function.
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The POWER peripheral is restricted while the SoftDevice is enabled, so USB VBUS presence must be read through sd_power_usbregstatus_get instead of machine's own USB detection.
This matters because TinyGo's machine layer never notices the cable being unplugged (the USB power SOC events are drained unhandled by this package's event pump), so on a battery-powered device with a serial monitor attached, machine.Serial.Write blocks forever once its TX ring fills up after unplug. Callers can guard debug output with this function.