[platformIO][Attiny426] Change internal clock frequency

[JorgeTorres01]

Hi,

I need to define the PWM frequency of 1kHz.

If I define the TCA0.SPLIT.CTRLA with TCA_SPLIT_CLKSEL_DIV64_gc the MCU generates a signal approx. 1,22 kHz (with TCA0.SPLIT.LPER = 0xff; TCA0.SPLIT.HPER = 0xff;)

If I define TCA0.SPLIT.CTRLA with TCA_SPLIT_CLKSEL_DIV256_gc the MCU generates a signal approx. 0,305 kHz (with TCA0.SPLIT.LPER = 0xff; TCA0.SPLIT.HPER = 0xff;). But the 1kHz achieved with TCA0.SPLIT.LPER = 0x4D; TCA0.SPLIT.HPER = 0x4D (77, DEC);

This way, I have a reduced duty cycle resolution. Is it possible to reduce the clock frequency from 20 to 16 MHz?

Thank you, Jorge

[JorgeTorres01]

In Arduino IDE it is possible to change the CPU frequency.

How can it be changed in code?

The check with F_CPU but it does not work.

[SpenceKonde]

there's a fusebit to set 16-derived vs 20 derived It is set to match selection whenever a sketch is uploiaded over UDPI. It cannnot be set with optoboot except by rebuning boootloader

This appliies to tinyAVR 0/1/2, megaAVR 0, and as far as we know upcoming EA-series:

The compliance of the oscillator is nothing sort of astonishing. Many times larger than the spec implies: the actual dffference between min and max clock speed (assuming the clock functioned atthe thigh end which it doesn't always at the high speed setting) See https://github.com/SpenceKonde/megaTinyCore/blob/master/megaavr/extras/Ref_Tunin.md

What are your actual requirements? What frequency How many vchannels? Whar eelse is goingfon .

Posting the full code and schematic wol help us help you

[JorgeTorres01]

Thank you SpenceKonde

I have this code on Arduino IDE with an internal clock of 16 MHz. I change the PER to 0xF8 to achieve a frequency of 1 kHz on PWM signals. And this works correctly

uint8_t WO0 = 9;
uint8_t WO1 = 8;
uint8_t WO4 = 0;
uint8_t WO5 = 1;

void setup () {
  TCA0.SPLIT.LPER = 0xF8;
  TCA0.SPLIT.HPER = 0xF8;

  TCA0.SPLIT.CTRLA = ~((~TCA0.SPLIT.CTRLA) | TCA_SPLIT_CLKSEL_DIV1_gc | TCA_SPLIT_CLKSEL_DIV2_gc | TCA_SPLIT_CLKSEL_DIV4_gc | TCA_SPLIT_CLKSEL_DIV8_gc | TCA_SPLIT_CLKSEL_DIV16_gc | TCA_SPLIT_CLKSEL_DIV64_gc | TCA_SPLIT_CLKSEL_DIV256_gc | TCA_SPLIT_CLKSEL_DIV1024_gc); 
  TCA0.SPLIT.CTRLA |= TCA_SPLIT_CLKSEL_DIV64_gc;

  pinMode(WO0, OUTPUT);
  pinMode(WO1, OUTPUT);
  pinMode(WO4, OUTPUT);
  pinMode(WO5, OUTPUT);

  analogWrite(WO0, 20);
  analogWrite(WO1, 70);
  analogWrite(WO4, 140);
  analogWrite(WO5, 200);
}

void loop () {
}

I'm trying to use PlatformIO instead of Arduino IDE because it's easier to organize and open functions... When I was writing this post, I saw that the PlatformIO uses a different platform (https://github.com/platformio/platform-atmelmegaavr.git)

Is it possible to use megaTinyCore on PlatformIO for attiny426?

[SpenceKonde]

I don't know anything about platform IO, other than that a alot of my users are on it. There may be an incomplete document in this repo about it because I don't know any of the relevant answers

iirc you have to manually specify the #defines in your configuration file. I suspect it defaults to 20

[SpenceKonde]

And this is by the way one of the most fustrating things about the widespread use of platform IO - I don't have a method to make sure that a valid combination of options is seleected

[SpenceKonde]

Closing. If anyone wants to help clarify the matter in the PlatformIO.md file, I gladly merge PRs

Edit (this way it's not in the notification, i think) But fixing this myself would require me learning a new IDE well enough to use it with a custom board package when I already have an IDE that works fine and will automatically install my board package and which I'm not particularly dissatisfied with (unlike Arduino's official core or hardware, both of which I have a very low opinion of, I don't dislike the IDE that much. As long as I don't open the serial monitor. The serial monitor is utter shit, but AFAIK nobody uses it except like, students without install privileges taking classes with it). Anyway, learning IDEs is not fun. Wrangling build tools is not fun, Doing projects is fun. Making tools is fun.