RESOLVED: Push-Pull and weak Pull up [Can they be activated together]?

selmesal · ‎2016-10-04

Posted on October 05, 2016 at 02:31

Hello,

If a pin is configured as Push Pull, can we still specify a pull up resistor to go with it?

(Is the pull up used to avoid floating conditions even in Push-Pull configurations?)

/**USART2 GPIO Configuration

PA2 ------> USART2_TX

PA3 ------> USART2_RX

*/

GPIO_InitStruct.Pin = GPIO_PIN_2|GPIO_PIN_3;

GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;

GPIO_InitStruct.Pull = GPIO_PULLUP;

GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;

GPIO_InitStruct.Alternate = GPIO_AF7_USART2;

HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

selmesal · ‎2016-10-04

Posted on October 05, 2016 at 04:17

ok, I think I understand it now.

GPIO_InitStruct.Mode = GPIO_MODE_AF_PP is relevant only to the output [Tx] pin of the UART port.

GPIO_InitStruct.Pull = GPIO_PULLUP applies only to the input [Rx] pin of the UART port.

Feel free to comment if you see it differently.

Uwe Bonnes · ‎2016-10-05

Posted on October 05, 2016 at 12:40

From what I understand, you can activate Pull (up|down) together with ush/pull output. However this does not make sense.