USB device support and usb_serial example #50
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kevswims
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This was tested on an STM32G473 on a custom board with an external 8MHz oscillator
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| //! This example currently requires an 8MHz external oscillator | ||
| //! and assumed an LED is connected to port A6. | ||
| //! | ||
| //! Further work could be done to setup the HSI48 and the clock |
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| // - APB1 = PCLK1 = 72 MHz | ||
| // - APB2 = PCLK2 = 72 MHz | ||
| // - USB = 48 MHz | ||
| let mut rcc = rcc.freeze( |
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Since we have the CRS support now this could be reworked to not depend on the HSE at all. Would make it easier to run on other hardware.
| configure_usb_clock_source(ClockSource::Hsi48, &rcc); | ||
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| // Configure an LED | ||
| let gpioa = dp.GPIOA.split(&mut rcc); |
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The LED is probably a distraction. Take it out to simplify stuff.
| .build(); | ||
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| loop { | ||
| if !usb_dev.poll(&mut [&mut serial]) { |
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A separate example or rework this one to poll in an interrupt would be good. Calling poll from the main loop is not super useful for anything but the most trivial of projects.
| @@ -85,3 +85,6 @@ pub mod syscfg; | |||
| pub mod time; | |||
| pub mod timer; | |||
| // pub mod watchdog; | |||
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| #[cfg(all(feature = "stm32-usbd", any(feature = "stm32g473",)))] | |||
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The machine feature needs changed here. Do all G4's have USB?
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Per ST's website, yes they all have USB. I've been bringing a G431 up and this is the only line that needed adjusting. G431 is the minimum spec G4 available.
| /// Sets up the clock recovery system for the HSI48 oscillator. | ||
| /// TODO: make this configurable for more than just USB applications. | ||
| pub fn configure(self, crs_config: CrsConfig, rcc: &Rcc) -> Self { | ||
| // TODO: This needs to ensure that the HSI48 is enabled |
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Some of this is done
| } | ||
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| #[inline(always)] | ||
| pub fn configure_usb_clock_source(cs: ClockSource, rcc: &Rcc) { |
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If the HSI48 is selected, can this do the configuration of it?
| q: Some(PllQDiv::DIV_6), | ||
| p: None, | ||
| }) | ||
| .ahb_psc(Prescaler::Div2) |
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Thought it was worth mentioning because I noticed in test, this div2 is setting the HCLK to 72Mhz -- differs from the comment above.
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I'm bringing up a g431 with usbd-serial and everything is working great so far. Works with CRS and with HSE+PLL configured for the 12Mhz crystal on a custom board. |
Draft PR to go in after the separate #49 to ease review.
This PR adds the following features:
This has been tested on a custom STM32F473 board. If desired I can split this out into separate PRs for the defmt/probe-run and the USB support.