How to generate HF clock output?

[ceremcem]

We are using ChibiOS STM32F407 Discovery Board (8Mhz XTAL) to generate a relatively high frequency output (500 kHz) with the following code:

Code: Select all

    static void squareWave(void *arg)
    {
        /* PB0 will be used for square wave
            use AlternateFunction.0 for digital io
        */
    
        palSetPadMode(GPIOB, 0, PAL_MODE_ALTERNATE(0));
       palSetPadMode(GPIOB, 0, PAL_MODE_OUTPUT_PUSHPULL);
    
        while(true)
        {
            palSetPad(GPIOB, 0);
            chThdSleepMicroseconds(1);
            palClearPad(GPIOB, 0);
            chThdSleepMicroseconds(1);
        }
    }

But the result is 10 kHz or so. What do we do wrong?

Edit

if `#define CH_CFG_ST_FREQUENCY 10000` remains in `chconf.h`, it does produce a 10 kHz output. When we change that value from 10000 to 1000000, it gives just about 100 kHz (99.8 kHz or so), but not 500 kHz. Also,

[Giovanni]

What version are you using?

For that kind of things better use the PWM driver anyway.

Giovanni

[ceremcem]

I'm using ChibiOS-3.x. Regarding to your suggestion, I wrote a simple variable frequency PWM generator:

https://github.com/ceremcem/chibi-test/ ... 282/main.c

It's dirty but it works.

Thank you for leading.

Note: I was not aware of your answer. Fixed this in the notification settings. Anyway, I'm sorry for the late response.

[Giovanni]

Hi,

I forgot to mention, there are also the MCO1 and MCO2 pins that can output any internal clock source. Depending on the frequency you need you may also consider them.

Giovanni

[ceremcem]

As per question, that would be a sensible option, but I omitted to say that I needed that kind of variable frequency. Since I was pretty sure about the code block that generates the squarewave, I thought I might change the sleep time as I wish at the end of this issue, but pwm driver does exacly what I would