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Add support for HSE bypass and CSS #156

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Oct 29, 2020
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1 change: 1 addition & 0 deletions CHANGELOG.md
Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
- SPI4 peripheral for supported
devices. ([#99](https://github.com/stm32-rs/stm32f3xx-hal/pull/99))
- Support for I2C transfer of more than 255 bytes, and 0 byte write ([#154](https://github.com/stm32-rs/stm32f3xx-hal/pull/154))
- Support for HSE bypass and CSS ([#156](https://github.com/stm32-rs/stm32f3xx-hal/pull/156))

### Changed

Expand Down
48 changes: 34 additions & 14 deletions src/rcc.rs
Original file line number Diff line number Diff line change
Expand Up @@ -21,13 +21,7 @@ impl RccExt for RCC {
apb1: APB1 { _0: () },
apb2: APB2 { _0: () },
bdcr: BDCR { _0: () },
cfgr: CFGR {
hse: None,
hclk: None,
pclk1: None,
pclk2: None,
sysclk: None,
},
cfgr: CFGR::default(),
}
}
}
Expand Down Expand Up @@ -87,7 +81,7 @@ impl AHB {
/// ```
/// let dp = pac::Peripherals::take().unwrap();
/// let rcc = dp.RCC.constrain();
/// use_ahb(&mut rcc.apb1)
/// use_apb1(&mut rcc.apb1)
/// ```
pub struct APB1 {
_0: (),
Expand All @@ -112,7 +106,7 @@ impl APB1 {
/// ```
/// let dp = pac::Peripherals::take().unwrap();
/// let rcc = dp.RCC.constrain();
/// use_ahb(&mut rcc.apb2)
/// use_apb2(&mut rcc.apb2)
/// ```
pub struct APB2 {
_0: (),
Expand Down Expand Up @@ -212,10 +206,13 @@ impl BDCR {
/// ```
/// let dp = pac::Peripherals::take().unwrap();
/// let rcc = dp.RCC.constrain();
/// use_ahb(&mut rcc.cfgr)
/// use_cfgr(&mut rcc.cfgr)
/// ```
#[derive(Default)]
pub struct CFGR {
hse: Option<u32>,
hse_bypass: bool,
css: bool,
hclk: Option<u32>,
pclk1: Option<u32>,
pclk2: Option<u32>,
Expand Down Expand Up @@ -296,6 +293,24 @@ impl CFGR {
self
}

/// Enable HSE bypass.
/// Uses user provided clock signal instead of an external oscillator.
/// OSC_OUT pin is free and can be used as GPIO.
/// No effect if HSE is not enabled.
pub fn bypass_hse(mut self) -> Self {
self.hse_bypass = true;
self
}

/// Enable CSS (Clock Security System).
/// System clock is automatically switched to HSI and an interrupt (CSSI) is generated
/// when HSE clock failure is detected.
/// No effect if HSE is not enabled.
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Maybe add a note, that a CSS Event can be catched via CSSI (RM0316 9.2.7)?

pub fn enable_css(mut self) -> Self {
self.css = true;
self
}

/// Sets a frequency for the AHB bus
pub fn hclk<F>(mut self, freq: F) -> Self
where
Expand Down Expand Up @@ -376,10 +391,11 @@ impl CFGR {
}

// PLL_MUL maximal value is 16
assert!(divisor <= 16);
// PRE_DIV maximal value is 16
assert!(multiplier <= 16);

// PRE_DIV maximal value is 16
assert!(divisor <= 16);

(multiplier, Some(divisor))
}
// HSI division is always divided by 2 and has no adjustable division
Expand Down Expand Up @@ -583,9 +599,13 @@ impl CFGR {

let rcc = unsafe { &*RCC::ptr() };

// enable HSE and wait for it to be ready
if self.hse.is_some() {
// enable HSE and wait for it to be ready
rcc.cr.modify(|_, w| w.hseon().on());
rcc.cr.modify(|_, w| {
w.hsebyp().bit(self.hse_bypass);
w.csson().bit(self.css);
w.hseon().on()
});

while rcc.cr.read().hserdy().is_not_ready() {}
}
Expand Down