STM32H723 unable to reach max clock

[acedogblast]

Hello I am using CubeMX to help setup the right settings for getting the maximum 550 MHz CPU clock on a STM32H723.

I get a runtime error due to d1cpre_clk <= d1cpre_clk_max . It seems on h.rs that the maximum clock at voltage scale 0 is 480MHz. I am not sure if I can simply make a custom cfg with the values for my MCU.

Additionally according to CubeMX it seems that to have a CPU clock higher than 520 MHz you have to set CPU_FREQ_BOOST in the flash option byte. Is there a way to do this in the current code?

For reference here is my peripheral config:

peripheral_config.rcc.hse = Some(Hse {
            freq: Hertz::mhz(25),
            mode: HseMode::Oscillator,
        });
        peripheral_config.rcc.pll1 = Some(Pll {
            source: PllSource::HSE,
            prediv: PllPreDiv::DIV2, // 12.5MHz needs to be between 1 to 16 MHz
            mul: PllMul::MUL44,
            divp: Some(PllDiv::DIV1), // 550 MHz system clock (maximum)
            divq: Some(PllDiv::DIV2), // 275 MHz
            divr: Some(PllDiv::DIV2), // 275 MHz
        });
        peripheral_config.rcc.pll2 = Some(Pll {
            source: PllSource::HSE,
            prediv: PllPreDiv::DIV2,
            mul: PllMul::MUL32,
            divp: Some(PllDiv::DIV2),
            divq: Some(PllDiv::DIV2),
            divr: Some(PllDiv::DIV2),
        });

        peripheral_config.rcc.sys = Sysclk::PLL1_P; // 550 MHz
        peripheral_config.rcc.d1c_pre = AHBPrescaler::DIV1; // 550 MHz
        peripheral_config.rcc.ahb_pre = AHBPrescaler::DIV2; // 275 MHz
        peripheral_config.rcc.apb1_pre = APBPrescaler::DIV2; // 137.5 MHz
        peripheral_config.rcc.apb2_pre = APBPrescaler::DIV2;
        peripheral_config.rcc.apb3_pre = APBPrescaler::DIV2;
        peripheral_config.rcc.apb4_pre = APBPrescaler::DIV2;

        peripheral_config.rcc.mux.i2c4sel = mux::I2c4sel::PCLK4; // 137.5 MHz
        peripheral_config.rcc.mux.i2c1235sel = mux::I2c1235sel::PCLK1;
        peripheral_config.rcc.mux.sdmmcsel = mux::Sdmmcsel::PLL2_R; // 200 MHz
        peripheral_config.rcc.mux.octospisel = mux::Fmcsel::HCLK3; // 200 MHz

        peripheral_config.rcc.supply_config = SupplyConfig::LDO;
        peripheral_config.rcc.voltage_scale = VoltageScale::Scale0;

[Dirbaio]

It seems on h.rs that the maximum clock at voltage scale 0 is 480MHz

It's 480 for some H7s, 550 for yours. Check you have the right chip feature in Cargo.toml

to have a CPU clock higher than 520 MHz you have to set CPU_FREQ_BOOST in the flash option byte. Is there a way to do this in the current code?

Not from firmware. Since it's an option byte you have to flash it with e.g. stm32cubeprog.

[acedogblast]

In my Cargo.toml:
embassy-stm32 = {version = "0.4.0", features = ["stm32h723zg", "time-driver-any", "exti", "unstable-pac"] }

The exact MCU I have is STM32H723ZGT6. This seems to match.

[Dirbaio]

that chip enables this code, which sets the max to 550 or 520 which is correct. Not sure what's going on.

Maybe you're using an old embassy-stm32 version? no, that code is the same on 0.4.0...

embassy/embassy-stm32/src/rcc/h.rs

Lines 524 to 537 in 5572b88

	#[cfg(pwr_h7rm0468)]
	let (d1cpre_clk_max, hclk_max, pclk_max) = match config.voltage_scale {
	VoltageScale::Scale0 => {
	let d1cpre_clk_max = if pac::SYSCFG.ur18().read().cpu_freq_boost() {
	550_000_000
	} else {
	520_000_000
	};
	(Hertz(d1cpre_clk_max), Hertz(275_000_000), Hertz(137_500_000))
	}
	VoltageScale::Scale1 => (Hertz(400_000_000), Hertz(200_000_000), Hertz(100_000_000)),
	VoltageScale::Scale2 => (Hertz(300_000_000), Hertz(150_000_000), Hertz(75_000_000)),
	VoltageScale::Scale3 => (Hertz(170_000_000), Hertz(85_000_000), Hertz(42_500_000)),
	};

[acedogblast]

Ok It seems to be working if I set the clock to 512.5MHz. So I do just have to set the option byte. If that works then I will close this. Thanks for the assistance.
Edit: It seems that setting the option byte in firmware is possible according to RM0468 4.4.2

[acedogblast]

Confirmed setting option byte allows the max clock to go to 550MHz.
I used stm32h7x option_write 0 0x074 0x4 openocd command to set it.