77 lines
2.2 KiB
Rust
77 lines
2.2 KiB
Rust
use crate::pac;
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pub enum HfclkSource {
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Internal,
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ExternalXtal,
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}
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pub enum LfclkSource {
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InternalRC,
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Synthesized,
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ExternalXtal,
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ExternalLowSwing,
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ExternalFullSwing,
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}
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#[non_exhaustive]
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pub struct Config {
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pub hfclk_source: HfclkSource,
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pub lfclk_source: LfclkSource,
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}
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impl Default for Config {
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fn default() -> Self {
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Self {
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// There are hobby nrf52 boards out there without external XTALs...
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// Default everything to internal so it Just Works. User can enable external
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// xtals if they know they have them.
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hfclk_source: HfclkSource::Internal,
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lfclk_source: LfclkSource::InternalRC,
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}
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}
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}
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/// safety: must only call once.
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pub unsafe fn configure(config: Config) {
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let r = &*pac::CLOCK::ptr();
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// Start HFCLK.
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match config.hfclk_source {
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HfclkSource::Internal => {}
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HfclkSource::ExternalXtal => {
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// Datasheet says this is likely to take 0.36ms
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r.events_hfclkstarted.write(|w| unsafe { w.bits(0) });
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r.tasks_hfclkstart.write(|w| unsafe { w.bits(1) });
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while r.events_hfclkstarted.read().bits() == 0 {}
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}
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}
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// Configure LFCLK.
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match config.lfclk_source {
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LfclkSource::InternalRC => r.lfclksrc.write(|w| w.src().rc()),
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LfclkSource::Synthesized => r.lfclksrc.write(|w| w.src().synth()),
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LfclkSource::ExternalXtal => r.lfclksrc.write(move |w| w.src().xtal()),
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LfclkSource::ExternalLowSwing => r.lfclksrc.write(move |w| {
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w.src().xtal();
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w.external().enabled();
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w.bypass().disabled();
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w
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}),
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LfclkSource::ExternalFullSwing => r.lfclksrc.write(move |w| {
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w.src().xtal();
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w.external().enabled();
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w.bypass().enabled();
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w
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}),
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}
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// Start LFCLK.
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// Datasheet says this could take 100us from synth source
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// 600us from rc source, 0.25s from an external source.
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r.events_lfclkstarted.write(|w| unsafe { w.bits(0) });
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r.tasks_lfclkstart.write(|w| unsafe { w.bits(1) });
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while r.events_lfclkstarted.read().bits() == 0 {}
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}
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