I have the STM32F4 discovery board. I want to use the GPIO to drive the gate of a power MOSFET up to 9V. Everything works well with push/pull output, then I configured the pin for open drain output, and add the resistors and 9V supply. I pulled the pin up to 9volts with 10kohm and down to ground with 1Mohm. The output looks fine when it's low, but when I try to toggle it high it just goes up like 0.1v but is still low.
I was looking at the output more, and I noticed there are protection diodes on the I/O pins. I think this might be my problem. Is it even possible to pull up the output pin above 3v when configured open drain? What is the max limit?