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Use type-safe enum for baud rate computation #1

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Use type-safe enum for baud rate computation #1

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275ccb9
Add reclock functionality for SPI
ceigel Apr 23, 2020
cbe725e
Use type-safe enum for baud rate computation
Sh3Rm4n May 6, 2020
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39 changes: 28 additions & 11 deletions src/spi.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@ use core::ptr;

use crate::hal::spi::FullDuplex;
pub use crate::hal::spi::{Mode, Phase, Polarity};
use crate::stm32::spi1;
use crate::stm32::{SPI1, SPI2, SPI3};
use nb;

Expand Down Expand Up @@ -114,6 +115,21 @@ pub struct Spi<SPI, PINS> {
pins: PINS,
}

#[inline]
fn compute_clock_variant(clocks: Hertz, freq: Hertz) -> spi1::cr1::BR_A {
match clocks.0 / freq.0 {
0 => unreachable!(),
1..=2 => spi1::cr1::BR_A::DIV2,
3..=5 => spi1::cr1::BR_A::DIV4,
6..=11 => spi1::cr1::BR_A::DIV8,
12..=23 => spi1::cr1::BR_A::DIV16,
24..=39 => spi1::cr1::BR_A::DIV32,
40..=95 => spi1::cr1::BR_A::DIV64,
96..=191 => spi1::cr1::BR_A::DIV128,
_ => spi1::cr1::BR_A::DIV256,
}
}

macro_rules! hal {
($($SPIX:ident: ($spiX:ident, $APBX:ident, $spiXen:ident, $spiXrst:ident, $pclkX:ident),)+) => {
$(
Expand Down Expand Up @@ -167,17 +183,7 @@ macro_rules! hal {
Polarity::IdleHigh => w.cpol().idle_high(),
};

match clocks.$pclkX().0 / freq.into().0 {
0 => unreachable!(),
1..=2 => w.br().div2(),
3..=5 => w.br().div4(),
6..=11 => w.br().div8(),
12..=23 => w.br().div16(),
24..=39 => w.br().div32(),
40..=95 => w.br().div64(),
96..=191 => w.br().div128(),
_ => w.br().div256(),
};
w.br().variant(compute_clock_variant(clocks.$pclkX(), freq.into()));

w.spe()
.enabled()
Expand All @@ -200,6 +206,17 @@ macro_rules! hal {
pub fn free(self) -> ($SPIX, (SCK, MISO, MOSI)) {
(self.spi, self.pins)
}

pub fn reclock<F>(&mut self, freq: F, clocks: Clocks)
where F: Into<Hertz>
{
self.spi.cr1.modify(|_, w| w.spe().disabled());
self.spi.cr1.modify(|_, w| {
w.br().variant(compute_clock_variant(clocks.$pclkX(), freq.into()));
w.spe().enabled()
});
}

}

impl<PINS> FullDuplex<u8> for Spi<$SPIX, PINS> {
Expand Down