STM32f407vet6 blackboard malfunctional PWM

[lobivan]

Hello, everyone. I've bought a STM32f407vet6 blackboard from China. It seems to work mostly well when speaking about digital inputs and outputs, but I have problems with the PWM, it doesn't start at all neither with

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analogWrite()

nor with

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pwmWrite()

. I have checked whether pins I use include PWM and I've also checked these pins with

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digitalWrite

and they work. I have initialized them both with

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pinMode(...,OUTPUT)

and

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pinMode(...,PWM)

but nothing helps with PWM at all. I don't know what to do with that issue, I've thought about timer settings, but i don't know how to work with registers and basic timer settings don't seem to have any effect at all. Did anyone have this problem?

[stevestrong]

viewtopic.php?f=2&t=301
Which core do you use?
Which IDE? Arduino?
Please post a simple sketch which hows the effect you are describing.

[lobivan]

Yes, I use Arduino IDE. Approximate code:

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#define PWMPin        PA8

int PWMval;

void setup() {

  Serial1.begin(9600);
  pinMode(PWMPin,PWM);


}

void loop() {

  PWMval = millis()%(65535);
  pwmWrite(PWMPin, PWMval);

}

Does not work also if PWMwrite is replaced with analogWrite (PWMis also replaced with OUTPUT ) or if 65535 is replaced with 255 or 1024. I mean, I've read that analogWrite works with numbers 0:255, so I've tried different combinatins. STM32F40xxx manual says the timer is 16-bit as well as the PWM, so 65535 should work, but it doesn't. I suppose the problem is in the timer. I guess it needs to be initialized in some way, but I do not know how. I also tried with pins PB15, PC8 and maybe other pins, don't remember exactly, they belong to different timers, so there is a little chance they are broken simultaneously

[stevestrong]

Which core do you use?

[fpiSTM]

I guess it is libmaple as STM32 core does not have pwmWrite API nor PWM as argument of pin mode.

[lobivan]

I use STM32 master pack as usually recommended everywhere. Exactly this one: https://github.com/rogerclarkmelbourne/Arduino_STM32 . I am much confused because in some examples the pwm is enabled in one line, in others you have to turn on timers via registers, but no one gives manual to f407, there are only f103 examples.

[lobivan]

I guess it is libmaple as STM32 core does not have pwmWrite API nor PWM as argument of pin mode.

I tried both pwmWrite and analogWrite, neither works

[stevestrong]

It is not enough to set the pin mode.
You have to setup the timer corresponding to the used pin (PA8 in your example is mapped to timer 1 channel 1, see here).
A usual setup looks like this:

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Timer1.init(); // initializes and stops the timer
pinMode(PA8, PWM); // sets the pin mode
Timer1.setPeriod(<micro_seconds>); // replace with your needed value
Timer1.resume(); // start the timer

Only after this you should use pwmWrite().

[lobivan]

It is not enough to set the pin mode.
You have to setup the timer corresponding to the used pin (PA8 in your example is mapped to timer 1 channel 1, see here).
A usual setup looks like this:

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Timer1.init(); // initializes and stops the timer
pinMode(PA8, PWM); // sets the pin mode
Timer1.setPeriod(<micro_seconds>); // replace with your needed value
Timer1.resume(); // start the timer

Only after this you should use pwmWrite().

Thank you, it helped, but TimerX.setPeriod is not nessesary, and I want to point out that the PWM works invertedly (0 = HIGH, 65535 = LOW)
For test I've switched to PA6 and LED_BUILTIN as it is more simple to operate this LED, and it uses TIM3. Also thanks for the table link. My code that works, the line with timerPeriod is commented

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int PWMval = 0;

void setup()
{
  
  Timer3.init();
  pinMode(PA6, PWM);
  //Timer3.setPeriod(1000);
  Timer3.refresh();
  Timer3.resume();
}

void loop() 
{

  PWMval = micros()%65535;
  pwmWrite(PA6,PWMval);
  
}

UPD: Seems like the only functional timer I have is Tim3 as no other seems to be working

[stevestrong]

Timerx.setPeriod() is necessary if you want to output PWM signal with a specific period, not identical with your case (maximum resolution 65535).