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GPIO13 driven low by ROM bootloader?

Posted: Wed Jun 17, 2020 8:30 am
by anszom
I have a board with some hardware attached to GPIO13. I notice that the GPIO13 line is driven low for about 20ms, before any of my code (including the in-flash bootloader) has a chance to run. This behaviour is not documented anywhere. Is this normal? Can this be disabled anyhow?

I've burned the DISABLE_JTAG fuse but it makes no difference.