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mboehmer

Odroid C2 GPIO initial state

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Armbianmonitor:

Hi,

I use the C2 connector J2 signals to control power distribution for several attaches devices.

A n-channel MOSFET is driven by a GPIO signal, with pulldown (3k3) to ensure that the n-channel MOSFET is off, - as long as the GPIO pin is in tristate or input state.

I considered this to be the case for all "normal" GPIO lines (except I2C and SPI).

I see now that after powerup, at least GPIOX_5 is active and switches on my load until I can export the GPIOX_5 and drive it low.

Does anyone know if the GPIO lines are driven actively after powerup / reset? And if so, can this behaviour be changed in U-boot or kernel environment?

The philosophy of the whole business is to keep everything shutdown except the C2 and the fiber media converter, so in case of bad things happening we can start without being disturbed by some external hardware.

 

Another issue seems to happen with the new kernel: I power the C2 by the J2 pins (+5V), with J1 removed. Old kernel was off after a "shutdown -h now", the current one is rebooting after this command.

This happens only if powered by J2 pins, not when powered by the small power connector - tested with two C2 boards now.

Any ideas on that?

 

Thanks in advance,

Michael

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