STM32F439 USART 2 RX Pin Pulls High when the USART2 is Enabled

[bnarciso]

Posted on March 08, 2014 at 04:04

I'm working with USART2 on the STM32F439 and when I enable the USART2 the RX Pin connected to PA3 pulls high to around 500 mV.I have initialized PA3 for the USART2 RX Pin as shown below. This pin is connected to a Microcontroller which has set it's GPIO as output with no pull up or pull down enabled. When I don't initialize the USART2 on the ARM PA3 is at 0V.

Is there an errata for the STM32F439?

1.
<
P
>gpioInit.GPIO_Pin = GPIO_Pin_3;<
BR
>gpioInit.GPIO_Speed = 
2.
GPIO_Speed_50MHz;<
BR
>gpioInit.GPIO_Mode = 
3.
GPIO_Mode_AF;<
BR
>gpioInit.GPIO_OType = 
4.
GPIO_OType_PP;<
BR
>gpioInit.GPIO_PuPd = GPIO_PuPd_NOPULL; </
P
> 
5.
<
P
>GPIO_Init( SYNC_MSP_USART_PORT, &gpioInit );</
P
>

Thanks for the help in advance!

[Tesla DeLorean]

Posted on March 08, 2014 at 04:33

So, have you configured which AF MUX is attached to the pin?

/* Connect USART2 pin to AF7 */
GPIO_PinAFConfig(GPIOA, GPIO_PinSource3, GPIO_AF_USART2); // PA3 (USART2_RX)