Problems with examples and timings

[rbarreiros]

Hello,

I'm starting with modm, so I started with the examples, I have a bluepill laying around, so I built the blink example, and all seemed working fine.

Right after, I tried the generic/usb example, the CDC one, built, flashed but USB was never recognized. To discard hardware issues I flashed some tinyusb examples I had around, and with latest (0.20) sure enough, it all works well.

I proceeded to try and figure out what's wrong, and setup a blinking led to debug, and noticed it wasn't blinking with the correct time (every 1 second toggle), if was taking loads of time, something like 10 seconds for each toggle, sure enough, switched to 100ms and it was blinking at 1 second (1 sec toggle), a really quick gdb showed the clock was indeed configured at 72MHz, so I assume it must be systick, which I guess it's probably at 4Hz ?

Anyway, all I did was git clone latest (develop), cd into modm/examples/blue_pill_f103/blink ; lbuild build ; scons build ; scons program and this behaviour remains.

Am I doing something wrong (or is this expected ?) or is this a bug and should open an issue ?

Kind regards,

[salkinium]

I did recently refactor the STM32F1 RCC system, maybe I messed something up.
Can you try a commit before this PR was merged? Or try the 2025q4 tag.

[rbarreiros]

Hello :)

Thank you for the quick reply. I did try the USB code with 2025q4 and q3, but I might have had other problems happening then, that were unrelated. I'll try it out ASAP.

[rbarreiros]

Good morning,

I can confirm the bug was introduced in develop, 2025q4 timings are working as expected, in develop it's like it's 10x slower, 100ms = 1s so defintely something to do with the clocking!

I do have the same problem with an stm32f3 (stm32f302cbt6), custom board (it's called AIOC, https://github.com/skuep/AIOC) which I'm thinking of porting to modm, using develop the timings are slowed 10x, and I'm unable to build the same project in 2025q4, I get loads of RCC related errors in board.hpp I created for this board I defined, probably due to the old RCC setup, I need to change the board.hpp in order to test it with 2025q4, but, I do get the same sympton than the stm32f1 in develop.

Kind regards,

[salkinium]

Can you share the system clock definitions for your board for the 10x slower case? It's suspicious to me that two different RCC implementations have 10x slower clocks, I would've expected maybe 2x slower or a power of two, but 10x is… weird.

(Sorry for the wait, was on back to back business trips)

[rbarreiros]

Sorry my late response, was out on work

Here is the Board.hpp I used to test with the latest version and gave me the wrong timings.

/*
 * Copyright (c) 2016-2018, Niklas Hauser
 * Copyright (c) 2017, Sascha Schade
 *
 * This file is part of the modm project.
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */
// ----------------------------------------------------------------------------

#ifndef MODM_STM32_NUCLEO_F302CB_HPP
#define MODM_STM32_NUCLEO_F302CB_HPP

#include <modm/platform.hpp>
#include <modm/architecture.hpp>
//#include <modm/debug.hpp>
#include <modm/architecture/interface/clock.hpp>
//#include <modm/debug/logger.hpp>
/// @ingroup modm_board_nucleo_f303re
//#define MODM_BOARD_HAS_LOGGER

using namespace modm::platform;
using namespace std::chrono_literals;

namespace Board
{
/// @ingroup modm_board_nucleo_f303re
/// @{
using namespace modm::literals;

/// STM32F302CB running at 72MHz generated from the external 8MHz clock
struct SystemClock
{
	static constexpr uint32_t Hse = 8_MHz;
	static constexpr Rcc::PllConfig pll{.Prediv = 1, .Mul = 9};
	static constexpr uint32_t Pll = Hse / pll.Prediv * pll.Mul;
	static_assert(Pll <= Rcc::MaxFrequency);

	static constexpr uint32_t Frequency = Pll;
	static constexpr uint32_t Ahb = Frequency;
	static constexpr uint32_t Apb1 = Frequency / 2;
	static constexpr uint32_t Apb2 = Frequency;

	static constexpr uint32_t Adc1   = Apb2;
	static constexpr uint32_t Adc2   = Apb2;

	static constexpr uint32_t Can    = Apb1;

	static constexpr uint32_t Spi1   = Apb2;
	static constexpr uint32_t Spi2   = Apb1;
	static constexpr uint32_t Spi3   = Apb1;

	// USART1 is on APB2 bus, but default clock is PCLK1
	static constexpr uint32_t Usart1 = Apb2; // Hmmmmm shouldn't it be APB2 ? @ 72mhz
	static constexpr uint32_t Usart2 = Apb1;
	static constexpr uint32_t Usart3 = Apb1;

	// I2C clock source is HSI by default
	static constexpr uint32_t I2c1 = Apb1;
	static constexpr uint32_t I2c2 = Apb1;

	static constexpr uint32_t Apb1Timer = Apb1 * 2;
	static constexpr uint32_t Apb2Timer = Apb2 * 1;
	static constexpr uint32_t Timer1  = Apb2Timer;
	static constexpr uint32_t Timer2  = Apb1Timer;
	static constexpr uint32_t Timer3  = Apb1Timer;
	static constexpr uint32_t Timer6  = Apb1Timer;
	static constexpr uint32_t Timer7  = Apb1Timer;
	static constexpr uint32_t Timer15 = Apb2Timer;
	static constexpr uint32_t Timer16 = Apb2Timer;
	static constexpr uint32_t Timer17 = Apb2Timer;

	static constexpr uint32_t Usb = Ahb / 1.5;
	static constexpr uint32_t Iwdg = Rcc::LsiFrequency;
	static constexpr uint32_t Rtc = Hse / 32;

	static bool inline
	enable()
	{
		Rcc::enableHseClock();

		Rcc::setFlashLatency<Frequency>();
		Rcc::updateCoreFrequency<Frequency>();

		Rcc::setAhbPrescaler(Rcc::AhbPrescaler::Div1);
		Rcc::setApb1Prescaler(Rcc::ApbPrescaler::Div2);
		Rcc::setApb2Prescaler(Rcc::ApbPrescaler::Div1);

		Rcc::enablePll(Rcc::PllSource::HsePrediv, pll);
		Rcc::enableSystemClock(Rcc::SystemClockSource::Pll);
		//Rcc::setUsbClockPrescaler(Rcc::UsbPrescaler::Div1_5);  // after PLL switch so USB = 48MHz
		Rcc::setRealTimeClockSource(Rcc::RealTimeClockSource::HseDiv32);
		
		return true;
	}
};

using LedGreen = GpioInverted<GpioOutputB8>;
using LedRed = GpioInverted<GpioOutputB9>;
using Leds = SoftwareGpioPort< LedGreen, LedRed >;

/// @}

//namespace stlink
//{
/// @ingroup modm_board_nucleo_f303re
/// @{
//using Rx = GpioInputA15;
//using Tx = GpioOutputA2;
//using Uart = BufferedUart<UsartHal2, UartTxBuffer<2048>>;
/// @}
//}

/// @ingroup modm_board_nucleo_f303re
/// @{
// No logger for now
//using LoggerDevice = modm::IODeviceWrapper< stlink::Uart, modm::IOBuffer::BlockIfFull >;
/*

namespace usb
{
	using Dm = GpioA11;
	using Dp = GpioA12;
	using Device = UsbFs;
} // usb namespace

*/
inline void
initialize()
{
	SystemClock::enable();
	SysTickTimer::initialize<SystemClock>();

	Leds::setOutput(modm::Gpio::Low);

	//stlink::Uart::connect<stlink::Tx::Tx, stlink::Rx::Rx>();
	//stlink::Uart::initialize<SystemClock, 115200_Bd>();
}
/// @}

/*
inline void
initializeUsb(uint8_t priority=2)
{
	usb::Device::initialize<SystemClock>(priority);
	usb::Device::connect<usb::Dm::Dm, usb::Dp::Dp>();
}
*/
} // Board namespace

#endif	// MODM_STM32_NUCLEO_F303RE_HPP

Kind regards,