embassy/examples/stm32f2/src/bin/pll.rs

#![no_std]
#![no_main]
#![feature(type_alias_impl_trait)]

use core::convert::TryFrom;

use defmt::*;
use embassy_executor::Spawner;
use embassy_stm32::time::Hertz;
use embassy_stm32::Config;
use embassy_time::Timer;
use {defmt_rtt as _, panic_probe as _};

#[embassy_executor::main]
async fn main(_spawner: Spawner) {
    // Example config for maximum performance on a NUCLEO-F207ZG board

    let mut config = Config::default();

    {
        use embassy_stm32::rcc::*;

        // By default, HSE on the board comes from a 8 MHz clock signal (not a crystal)
        config.rcc.hse = Some(Hse {
            freq: Hertz(8_000_000),
            mode: HseMode::Bypass,
        });
        // PLL uses HSE as the clock source
        config.rcc.pll_src = PllSource::HSE;
        config.rcc.pll = Some(Pll {
            // 8 MHz clock source / 8 = 1 MHz PLL input
            prediv: unwrap!(PllPreDiv::try_from(8)),
            // 1 MHz PLL input * 240 = 240 MHz PLL VCO
            mul: unwrap!(PllMul::try_from(240)),
            // 240 MHz PLL VCO / 2 = 120 MHz main PLL output
            divp: Some(PllPDiv::DIV2),
            // 240 MHz PLL VCO / 5 = 48 MHz PLL48 output
            divq: Some(PllQDiv::DIV5),
            divr: None,
        });
        // System clock comes from PLL (= the 120 MHz main PLL output)
        config.rcc.sys = Sysclk::PLL1_P;
        // 120 MHz / 4 = 30 MHz APB1 frequency
        config.rcc.apb1_pre = APBPrescaler::DIV4;
        // 120 MHz / 2 = 60 MHz APB2 frequency
        config.rcc.apb2_pre = APBPrescaler::DIV2;
    }

    let _p = embassy_stm32::init(config);

    loop {
        Timer::after_millis(1000).await;
        info!("1s elapsed");
    }
}