Problem to reach high Frequency on GPIO

[Lex Trc]

Posted on August 25, 2017 at 16:34

Hi,

i'm using stm32 nucleo board. The oscillator is configured to 32MHz speed.

Now, if i use the easy following code in the main:

while(1)

{

   HAL_GPIO_WritePin(LD2_GPIO_Port, LD2_Pin, 1);

   HAL_GPIO_WritePin(LD2_GPIO_Port, LD2_Pin, 0);

}

the frequency i measure on the LD2 pin is only 750KHz. This is really strange, i expect

to run more quick than 750KHz only.

Can someone help me?

[Tesla DeLorean]

Posted on August 25, 2017 at 16:39

Confirm what the CPU is running at internally. Internal clocks can be output via PA8 MCO pin.

Use a lighter abstraction. Use optimization

Use GPIO BSRR register in a direct write approach

>>stm32 nucleo board

That narrows the list to a 50+ boards, care to be more precise?

[Lex Trc]

Posted on August 25, 2017 at 16:46

The board is a Nucleo L053R8. How can i send output frequency on PA08?

[S.Ma]

Posted on August 25, 2017 at 17:02

The HAL code favours portability at the expense of speed which is the purpose of the LL (low layer).

Get LL cube examples from nucleo or discovery boards.

[Tesla DeLorean]

Posted on August 25, 2017 at 17:09

Seek out the MCO examples in your chosen library. Review RCC registers in IDE of choice to confirm PLL and clock source settings.

For PA8 driving via BSRR

while(1)

{

GPIOA->BSRR = (1 << 8);

GPIOA->BRR = (1 << 8);

}

Better to drive pin with a TIM

[Lex Trc]

Posted on September 12, 2017 at 14:15

thanks everybody