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//! OneWire pio driver
use crate::pio::{Common, Config, Instance, LoadedProgram, PioPin, ShiftConfig, ShiftDirection, StateMachine};
/// This struct represents an onewire driver program
pub struct PioOneWireProgram<'a, PIO: Instance> {
prg: LoadedProgram<'a, PIO>,
}
impl<'a, PIO: Instance> PioOneWireProgram<'a, PIO> {
/// Load the program into the given pio
pub fn new(common: &mut Common<'a, PIO>) -> Self {
let prg = pio::pio_asm!(
r#"
.wrap_target
again:
pull block
mov x, osr
jmp !x, read
write:
set pindirs, 1
set pins, 0
loop1:
jmp x--,loop1
set pindirs, 0 [31]
wait 1 pin 0 [31]
pull block
mov x, osr
bytes1:
pull block
set y, 7
set pindirs, 1
bit1:
set pins, 0 [1]
out pins,1 [31]
set pins, 1 [20]
jmp y--,bit1
jmp x--,bytes1
set pindirs, 0 [31]
jmp again
read:
pull block
mov x, osr
bytes2:
set y, 7
bit2:
set pindirs, 1
set pins, 0 [1]
set pindirs, 0 [5]
in pins,1 [10]
jmp y--,bit2
jmp x--,bytes2
.wrap
"#,
);
let prg = common.load_program(&prg.program);
Self { prg }
}
}
/// Pio backed OneWire driver
pub struct PioOneWire<'d, PIO: Instance, const SM: usize> {
sm: StateMachine<'d, PIO, SM>,
}
impl<'d, PIO: Instance, const SM: usize> PioOneWire<'d, PIO, SM> {
/// Create a new instance the driver
pub fn new(
common: &mut Common<'d, PIO>,
mut sm: StateMachine<'d, PIO, SM>,
pin: impl PioPin,
program: &PioOneWireProgram<'d, PIO>,
) -> Self {
let pin = common.make_pio_pin(pin);
let mut cfg = Config::default();
cfg.use_program(&program.prg, &[]);
cfg.set_out_pins(&[&pin]);
cfg.set_in_pins(&[&pin]);
cfg.set_set_pins(&[&pin]);
cfg.shift_in = ShiftConfig {
auto_fill: true,
direction: ShiftDirection::Right,
threshold: 8,
};
cfg.clock_divider = 255_u8.into();
sm.set_config(&cfg);
sm.set_enable(true);
Self { sm }
}
/// Write bytes over the wire
pub async fn write_bytes(&mut self, bytes: &[u8]) {
self.sm.tx().wait_push(250).await;
self.sm.tx().wait_push(bytes.len() as u32 - 1).await;
for b in bytes {
self.sm.tx().wait_push(*b as u32).await;
}
}
/// Read bytes from the wire
pub async fn read_bytes(&mut self, bytes: &mut [u8]) {
self.sm.tx().wait_push(0).await;
self.sm.tx().wait_push(bytes.len() as u32 - 1).await;
for b in bytes.iter_mut() {
*b = (self.sm.rx().wait_pull().await >> 24) as u8;
}
}
}