STM32L4R9I-EVAL Problems to use UART1 PB7 (rx) and PG9 (tx)

[LPers]

Dear community,

I've been playing with the STM32L4R9I-Eval board and it seems that I can't drive the PG9 pin.

My plan is to use the UART1 with the following pins:

• PB7 (rx)
• PG9 (tx).

I checked the documentation and to use PG9 you have to:

• Remove R236
• Open SB34

I did that changes and it seems that the uC still can't drive the PG9 pin. I'm checking with an oscilloscope on the connector CN14. Before initializing the UART I added a routine to set/reset the pins few times and it seems that the PG9 can't be driven by the uC.

I enabled the clock to the port G and configure the GPIO as all the others, but still can't drive it.

Any clue on what can be possible wrong?

[LPers]

One more information about it, I'm using the HAL lib. This is what I'm doing:

__HAL_RCC_GPIOG_CLK_ENABLE();
GPIO_InitTypeDef GPIO_InitStruct = {0};
GPIO_InitStruct.Pin    = GPIO_PIN_9;
GPIO_InitStruct.Mode   = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull   = GPIO_NOPULL;
GPIO_InitStruct.Speed   = GPIO_SPEED_LOW;
HAL_GPIO_Init(GPIOG, &GPIO_InitStruct);
 
while(1)
{
  HAL_GPIO_WritePin(GPIOG, GPIO_PIN_9, GPIO_PIN_SET);
  HAL_GPIO_WritePin(GPIOG, GPIO_PIN_9, GPIO_PIN_RESET);
}

I removed the code to all the other pins, so the code works.

[Tesla DeLorean]

GPIO G bank must have VCCIO explicitly enabled.​

[LPers]

Hi @Community member​ 

Thanks for the reply. I tried your suggestion and there's still no changes :(

According to my CubeMX project, the following should be done:

So I added that on my initialization:

__HAL_RCC_GPIOG_CLK_ENABLE();
HAL_PWREx_EnableVddIO2();
 
... same stuff as before

Still no output on the PG9.

[waclawek.jan]

PWR clock was enabled before that command? Read back the related register in debugger and check.

Is the VDDIO2 pin physically connected to power supply?

JW

[LPers.847]

Hi @Community member​ 

The VDDIO2 pin is physically connected to the power supply.

Now it's working, it was missing the enable PWR clock call.

Thank you very much guys.