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rpll: remove redundant time tracking

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This commit is contained in:
Robert Jördens 2021-01-31 13:42:15 +01:00
parent 6b2d8169f0
commit ab20d67a07
2 changed files with 15 additions and 15 deletions
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28
dsp/src/rpll.rs
View File

@ -6,7 +6,6 @@
#[derive(Copy, Clone, Default)]
pub struct RPLL {
dt2: u8, // 1 << dt2 is the counter rate to update() rate ratio
t: i32, // current counter time
x: i32, // previous timestamp
ff: u32, // current frequency estimate from frequency loop
f: u32, // current frequency estimate from both frequency and phase loop
@ -18,14 +17,12 @@ impl RPLL {
///
/// Args:
/// * dt2: inverse update() rate. 1 << dt2 is the counter rate to update() rate ratio.
/// * t: Counter time. Counter value at the first update() call. Typically 0.
///
/// Returns:
/// Initialized RPLL instance.
pub fn new(dt2: u8, t: i32) -> RPLL {
pub fn new(dt2: u8) -> RPLL {
RPLL {
dt2,
t,
..Default::default()
}
}
@ -69,7 +66,7 @@ impl RPLL {
// Update frequency lock
self.ff = self.ff.wrapping_add(p_ref.wrapping_sub(p_sig) as u32);
// Time in counter cycles between timestamp and "now"
let dt = self.t.wrapping_sub(x);
let dt = x.wrapping_neg() & ((1 << self.dt2) - 1);
// Reference phase estimate "now"
let y_ref = ((self.f >> self.dt2) as i32).wrapping_mul(dt);
// Phase error
@ -79,8 +76,6 @@ impl RPLL {
.ff
.wrapping_add((dy >> (shift_phase - self.dt2)) as u32);
}
// Advance time
self.t = self.t.wrapping_add(1 << self.dt2);
(self.y, self.f)
}
}
@ -95,7 +90,7 @@ mod test {
#[test]
fn make() {
let _ = RPLL::new(8, 0);
let _ = RPLL::new(8);
}
struct Harness {
@ -106,6 +101,7 @@ mod test {
noise: i32,
period: i32,
next: i32,
next_noisy: i32,
time: i32,
rng: StdRng,
}
@ -113,13 +109,14 @@ mod test {
impl Harness {
fn default() -> Self {
Harness {
rpll: RPLL::new(8, 0),
rpll: RPLL::new(8),
dt2: 8,
shift_frequency: 9,
shift_phase: 8,
noise: 0,
period: 333,
next: 111,
next_noisy: 111,
time: 0,
rng: StdRng::seed_from_u64(42),
}
@ -129,10 +126,12 @@ mod test {
let mut y = Vec::<f32>::new();
let mut f = Vec::<f32>::new();
for _ in 0..n {
let timestamp = if self.time - self.next >= 0 {
let p_noise = self.rng.gen_range(-self.noise..=self.noise);
let timestamp = self.next.wrapping_add(p_noise);
let timestamp = if self.time - self.next_noisy >= 0 {
assert!(self.time - self.next_noisy < 1 << self.dt2);
let timestamp = self.next_noisy;
self.next = self.next.wrapping_add(self.period);
let p_noise = self.rng.gen_range(-self.noise..=self.noise);
self.next_noisy = self.next.wrapping_add(p_noise);
Some(timestamp)
} else {
None
@ -197,7 +196,7 @@ mod test {
let (fm, fs, ym, ys) = h.measure(1 << 16);
assert!(fm.abs() < 1e-6);
assert!(fs.abs() < 6e-4);
assert!(ym.abs() < 2e-4);
assert!(ym.abs() < 4e-4);
assert!(ys.abs() < 2e-4);
}
@ -216,7 +215,8 @@ mod test {
assert!(ys.abs() < 1e-4);
}
/*#[test]
/*
#[test]
fn narrow_slow() {
let mut h = Harness::default();
h.period = 1818181;

2
src/bin/lockin.rs
View File

@ -53,7 +53,7 @@ const APP: () = {
// Configure the microcontroller
let (mut stabilizer, _pounder) = hardware::setup(c.core, c.device);
let pll = RPLL::new(ADC_SAMPLE_TICKS_LOG2 + SAMPLE_BUFFER_SIZE_LOG2, 0);
let pll = RPLL::new(ADC_SAMPLE_TICKS_LOG2 + SAMPLE_BUFFER_SIZE_LOG2);
let lockin = Lockin::new(
&iir_int::IIRState::lowpass(1e-3, 0.707, 2.), // TODO: expose