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I want to use a STM32F3 GPIO (3.6V) to drive another device using 5V input. Which is the correct way to do so?

I know that is possible to use the open drain mode on the GPIO, but I'm not sure if I need to connect an external 10K resistor with 5V power supply or the system is already included in the board for this purpose.

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STM32F3's have outputs for which you can pull them up or pull them down one every DIO when you configure your ports. I believe they will be pulled up to Vcc, so instead you would want to do this with an open drain and the bit externally pulled up to 5V high. Be sure to use 5V tolerant pins.

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  • \$\begingroup\$ @bitsmack That's pretty much what I was trying to say. You would use open drain and an EXTERNAL pull-up, even though there are internal pullups to Vcc available through configuration. \$\endgroup\$ Commented Jun 26, 2014 at 16:21
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According to the STM32F303VCT6 data sheet pins PE2 - PE6 are 5V-tolerant, as are PF9 and PF10 and several other pins. It would be safest to use those for driving 5V inputs with them set to open-drain outputs with the correct value pull-up resistor.

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