48 lines
1.3 KiB
Rust
48 lines
1.3 KiB
Rust
use crate::device::sys_timer::sleep;
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use fugit::MegahertzU32;
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use stm32f4xx_hal::{
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hal::{spi::SpiBus, digital::OutputPin},
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spi,
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};
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/// SPI Mode 1
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pub const SPI_MODE: spi::Mode = spi::Mode {
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polarity: spi::Polarity::IdleLow,
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phase: spi::Phase::CaptureOnSecondTransition,
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};
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// MAX Clock Frequency: 30MHz | SPI1 Max Frequency 42MHz
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pub const SPI_CLOCK_MHZ: MegahertzU32 = MegahertzU32::from_raw(21);
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pub const MAX_VALUE: u32 = 0x3FFFF;
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pub struct Dac<SPI: SpiBus<u8>, S: OutputPin> {
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spi: SPI,
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sync: S,
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}
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impl<SPI: SpiBus<u8>, S: OutputPin> Dac<SPI, S> {
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pub fn new(spi: SPI, mut sync: S) -> Self {
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let _ = sync.set_low();
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Dac { spi, sync }
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}
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fn write(&mut self, buf: &mut [u8]) -> Result<(), SPI::Error> {
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// pulse sync to start a new transfer. leave sync idle low
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// afterwards to save power as recommended per datasheet.
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let _ = self.sync.set_high();
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// must be high for >= 33 ns
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sleep(1);
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let _ = self.sync.set_low();
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self.spi.transfer_in_place(buf)?;
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Ok(())
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}
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pub fn set(&mut self, value: u32) -> Result<u32, SPI::Error> {
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let value = value.min(MAX_VALUE);
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let mut buf = [(value >> 14) as u8, (value >> 6) as u8, (value << 2) as u8];
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self.write(&mut buf)?;
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Ok(value)
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}
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}
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