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Merge pull request #2887 from jamesmunns/james/stm32-i2cv1-errata

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stm32: Add workaround for STM32 i2cv1 errata
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Dario Nieuwenhuis 2024-04-29 12:06:08 +00:00 committed by GitHub
commit 679160a1c5
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1 changed files with 26 additions and 0 deletions
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embassy-stm32/src/i2c/v1.rs
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@ -48,6 +48,32 @@ impl<'d, T: Instance, M: PeriMode> I2c<'d, T, M> {
//reg.set_anfoff(false);
});
// Errata: "Start cannot be generated after a misplaced Stop"
//
// > If a master generates a misplaced Stop on the bus (bus error)
// > while the microcontroller I2C peripheral attempts to switch to
// > Master mode by setting the START bit, the Start condition is
// > not properly generated.
//
// This also can occur with falsely detected STOP events, for example
// if the SDA line is shorted to low.
//
// The workaround for this is to trigger the SWRST line AFTER power is
// enabled, AFTER PE is disabled and BEFORE making any other configuration.
//
// It COULD be possible to apply this workaround at runtime, instead of
// only on initialization, however this would require detecting the timeout
// or BUSY lockup condition, and re-configuring the peripheral after reset.
//
// This presents as an ~infinite hang on read or write, as the START condition
// is never generated, meaning the start event is never generated.
T::regs().cr1().modify(|reg| {
reg.set_swrst(true);
});
T::regs().cr1().modify(|reg| {
reg.set_swrst(false);
});
let timings = Timings::new(T::frequency(), freq);
T::regs().cr2().modify(|reg| {