usart RX pin configure

[David.Cheng]

WHICH ONE IS BEST?

i have seen three methods:

1, in_floating http://www.micromouseonline.com/2009/12/31/stm32-usart-basics/

2, GPIO_MODE_AF_OD https://visualgdb.com/tutorials/arm/stm32/uart/hal/

3, GPIO_MODE_AF_PP

[Tesla DeLorean]

Floating is a method used in the F1 series. For the F4 use AF_PP and let the peripheral control the pin driver internally.

For things like I2C pins use AF_OD​