Arm Cortex STM32F405 Toggle pin at 20MHz?

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btbass

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I have a STM32F405 and I need to toggle an I/O pin at 20MHz.
Could anybody suggest how to do this?
Would inline assembler be the answer?
If so, how?
 

What is the maximum value of peripheral clock frequency?

What Oscillator frequency you have chosen ?

What is the minimum prescalar for Timer ?

- - - Updated - - -

Here is some example code, STM32F4: Timer

The timer can operate in the peripheral frequency of 168MHz, but obviously you can not use this code because it will have lot of delays when interpreting c to assembly, So you have to use PWM.
 

Thanks for the replies, I will look at the sample code.

I am using EmBlocks and the bare metal GCC compiler.
My core clock is 168MHz and the peripheral clock is 84MHz.

I have tried using the timer and also PWM.
The fastest I can go with these methods is ~2MHz?

Using C, if I just toggle the pin, I get < 2MHz.

while(1)
{
GPIO_SetBits(GPIOC, GPIO_Pin_12);
GPIO_ResetBits(GPIOC, GPIO_Pin_12);
}

I think I need inline assembler?
 

I will have a view on STM32F405 it look easy to do with PWM.

Doing with assembly will also difficult in case of 32 bit controllers.

So better you stick with PWM.

In LPC series you can generate 1/4 peripheral frequency, but still it will come like 164 / 8 = 20.5MHZ

Otherwise you have to select a peripheral frequency like 160MHz..

I will confirm the possibility after looking at manual.
 

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