embassy/examples/rpi-pico-w/src/pio.rs

use core::slice;

use cyw43::SpiBusCyw43;
use embassy_rp::dma::Channel;
use embassy_rp::gpio::{Pin, Pull};
use embassy_rp::pio::{PioStateMachine, ShiftDirection};
use embassy_rp::relocate::RelocatedProgram;
use embassy_rp::{pio_instr_util, Peripheral};
use embedded_hal_1::spi::ErrorType;
use embedded_hal_async::spi::SpiBusFlush;
use pio::Wrap;
use pio_proc::pio_asm;

pub struct PioSpi<SM, DMA> {
    // cs: Output<'static, AnyPin>,
    sm: SM,
    dma: DMA,
    wrap_target: u8,
}

impl<SM, DMA> PioSpi<SM, DMA>
where
    SM: PioStateMachine,
    DMA: Channel,
{
    pub fn new<DIO, CLK>(
        mut sm: SM,
        // cs: AnyPin,
        dio: DIO,
        clk: CLK,
        dma: DMA,
    ) -> Self
    where
        DIO: Pin,
        CLK: Pin,
    {
        let program = pio_asm!(
            ".side_set 1"
            // "set pindirs, 1 side 0"
            // "set pins, 0    side 0"
            ".wrap_target"
            "lp:",
            "out pins, 1    side 0"
            "jmp x-- lp     side 1"
            "set pindirs, 0 side 0"
            // "nop            side 1"
            "lp2:"
            "in pins, 1     side 0"
            "jmp y-- lp2    side 1"
            ".wrap"
        );

        let relocated = RelocatedProgram::new(&program.program);

        let mut pin_io = sm.make_pio_pin(dio);
        pin_io.set_pull(Pull::Down);
        pin_io.set_schmitt(true);
        let pin_clk = sm.make_pio_pin(clk);

        sm.write_instr(relocated.origin() as usize, relocated.code());

        // 16 Mhz
        sm.set_clkdiv(0x07d0);

        // 8Mhz
        sm.set_clkdiv(0x0a_00);

        // 1Mhz
        // sm.set_clkdiv(0x7d_00);

        // slowest possible
        // sm.set_clkdiv(0xffff_00);

        sm.set_autopull(true);
        // sm.set_pull_threshold(32);
        sm.set_autopush(true);
        // sm.set_push_threshold(32);

        sm.set_out_pins(&[&pin_io]);
        sm.set_in_base_pin(&pin_io);

        sm.set_set_pins(&[&pin_clk]);
        pio_instr_util::set_pindir(&mut sm, 0b1);
        sm.set_set_pins(&[&pin_io]);
        pio_instr_util::set_pindir(&mut sm, 0b1);

        sm.set_sideset_base_pin(&pin_clk);
        sm.set_sideset_count(1);

        sm.set_out_shift_dir(ShiftDirection::Left);
        sm.set_in_shift_dir(ShiftDirection::Left);

        let Wrap { source, target } = relocated.wrap();
        sm.set_wrap(source, target);

        // pull low for startup
        pio_instr_util::set_pin(&mut sm, 0);

        Self {
            // cs: Output::new(cs, Level::High),
            sm,
            dma,
            wrap_target: target,
        }
    }

    pub async fn write(&mut self, write: &[u32]) {
        let write_bits = write.len() * 32 - 1;
        let read_bits = 31;

        defmt::trace!("write={} read={}", write_bits, read_bits);

        let mut dma = Peripheral::into_ref(&mut self.dma);
        pio_instr_util::set_x(&mut self.sm, write_bits as u32);
        pio_instr_util::set_y(&mut self.sm, read_bits as u32);
        pio_instr_util::set_pindir(&mut self.sm, 0b1);
        pio_instr_util::exec_jmp(&mut self.sm, self.wrap_target);

        self.sm.set_enable(true);

        self.sm.dma_push(dma.reborrow(), write).await;

        let mut status = 0;
        self.sm.dma_pull(dma, slice::from_mut(&mut status)).await;
        defmt::trace!("{:#08x}", status);

        self.sm.set_enable(false);
    }

    pub async fn cmd_read(&mut self, cmd: u32, read: &mut [u32]) {
        let write_bits = 31;
        let read_bits = read.len() * 32 - 1;

        defmt::trace!("write={} read={}", write_bits, read_bits);

        let mut dma = Peripheral::into_ref(&mut self.dma);
        pio_instr_util::set_y(&mut self.sm, read_bits as u32);
        pio_instr_util::set_x(&mut self.sm, write_bits as u32);
        pio_instr_util::set_pindir(&mut self.sm, 0b1);
        pio_instr_util::exec_jmp(&mut self.sm, self.wrap_target);
        // self.cs.set_low();
        self.sm.set_enable(true);

        self.sm.dma_push(dma.reborrow(), slice::from_ref(&cmd)).await;
        self.sm.dma_pull(dma, read).await;

        self.sm.set_enable(false);
    }
}

#[derive(Debug)]
pub enum PioError {}

impl embedded_hal_async::spi::Error for PioError {
    fn kind(&self) -> embedded_hal_1::spi::ErrorKind {
        embedded_hal_1::spi::ErrorKind::Other
    }
}

impl<SM, DMA> ErrorType for PioSpi<SM, DMA>
where
    SM: PioStateMachine,
{
    type Error = PioError;
}

impl<SM, DMA> SpiBusFlush for PioSpi<SM, DMA>
where
    SM: PioStateMachine,
{
    async fn flush(&mut self) -> Result<(), Self::Error> {
        Ok(())
    }
}

impl<SM, DMA> SpiBusCyw43<u32> for PioSpi<SM, DMA>
where
    SM: PioStateMachine,
    DMA: Channel,
{
    async fn cmd_write<'a>(&'a mut self, write: &'a [u32]) -> Result<(), Self::Error> {
        self.write(write).await;
        Ok(())
    }

    async fn cmd_read<'a>(&'a mut self, write: &'a [u32], read: &'a mut [u32]) -> Result<(), Self::Error> {
        self.cmd_read(write[0], read).await;
        Ok(())
    }
}