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Tristating GPIO as an output

Question asked by naphtali on Feb 5, 2014
Latest reply on Feb 6, 2014 by naphtali
Using an STM32F407, can you have a pin set up as an output and tristated?

The reason that I ask is b/c my circuit is acting like it is doing just that. With my pin configuration as follows:

GPIO_InitStructure.GPIO_Mode   = GPIO_Mode_AF;
GPIO_Speed                           = GPIO_Speed_100MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd    = GPIO_PuPd_NOPULL;

GPIO_InitStructure.GPIO_Pin = PIN1_GPIO_PINx | PIN2_GPIO_PINx;
GPIO_Init(SCSS_GPIOX, &GPIO_InitStructure);$      

The output was acting like it was high impedance at times. I know this because it was getting signals from nearby traces coupled in, but that all went away if I enabled the internal pulldown