commit
08cc2e4840
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@ -12,7 +12,6 @@ impl Accu {
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impl Iterator for Accu {
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type Item = i32;
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#[inline]
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fn next(&mut self) -> Option<i32> {
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let s = self.state;
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self.state = self.state.wrapping_add(self.step);
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@ -14,7 +14,6 @@ impl Complex<i32> {
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/// Complex::<i32>::from_angle(1 << 30); // pi/2
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/// Complex::<i32>::from_angle(-1 << 30); // -pi/2
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/// ```
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#[inline(always)]
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pub fn from_angle(angle: i32) -> Self {
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let (c, s) = cossin(angle);
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Self(c, s)
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@ -48,6 +48,15 @@ pub struct IIR {
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}
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impl IIR {
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pub const fn new(gain: f32, y_min: f32, y_max: f32) -> Self {
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Self {
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ba: Vec5([gain, 0., 0., 0., 0.]),
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y_offset: 0.,
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y_min,
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y_max,
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}
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}
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/// Configures IIR filter coefficients for proportional-integral behavior
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/// with gain limit.
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///
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@ -3,38 +3,6 @@
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use core::ops::{Add, Mul, Neg};
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/// Bit shift, round up half.
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///
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/// # Arguments
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///
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/// `x` - Value to shift and round.
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/// `shift` - Number of bits to right shift `x`.
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///
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/// # Returns
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///
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/// Shifted and rounded value.
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#[inline(always)]
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pub fn shift_round(x: i32, shift: usize) -> i32 {
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(x + (1 << (shift - 1))) >> shift
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}
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/// Integer division, round up half.
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///
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/// # Arguments
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///
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/// `dividend` - Value to divide.
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/// `divisor` - Value that divides the
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/// dividend. `dividend`+`divisor`-1 must be inside [i64::MIN,
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/// i64::MAX].
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///
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/// # Returns
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///
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/// Divided and rounded value.
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#[inline(always)]
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pub fn divide_round(dividend: i64, divisor: i64) -> i64 {
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(dividend + (divisor - 1)) / divisor
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}
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fn abs<T>(x: T) -> T
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where
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T: PartialOrd + Default + Neg<Output = T>,
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@ -14,10 +14,7 @@ impl Lockin {
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/// Create a new Lockin with given IIR coefficients.
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pub fn new(ba: Vec5) -> Self {
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Self {
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iir: IIR {
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ba,
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..Default::default()
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},
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iir: IIR { ba },
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state: [Vec5::default(); 2],
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}
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}
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@ -49,7 +49,7 @@ impl RPLL {
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shift_frequency: u8,
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shift_phase: u8,
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) -> (i32, u32) {
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debug_assert!(shift_frequency > self.dt2);
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debug_assert!(shift_frequency >= self.dt2);
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debug_assert!(shift_phase >= self.dt2);
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// Advance phase
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self.y = self.y.wrapping_add(self.f as i32);
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@ -66,7 +66,7 @@ impl RPLL {
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// Reference phase (1 << dt2 full turns) with gain/attenuation applied
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let p_ref = 1u32 << (32 + self.dt2 - shift_frequency);
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// Update frequency lock
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self.ff = self.ff.wrapping_add(p_ref.wrapping_sub(p_sig) as u32);
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self.ff = self.ff.wrapping_add(p_ref.wrapping_sub(p_sig));
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// Time in counter cycles between timestamp and "now"
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let dt = (x.wrapping_neg() & ((1 << self.dt2) - 1)) as u32;
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// Reference phase estimate "now"
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@ -122,6 +122,10 @@ mod test {
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}
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fn run(&mut self, n: usize) -> (Vec<f32>, Vec<f32>) {
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assert!(self.period >= 1 << self.dt2);
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assert!(self.period < 1 << self.shift_frequency);
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assert!(self.period < 1 << self.shift_phase + 1);
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let mut y = Vec::<f32>::new();
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let mut f = Vec::<f32>::new();
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for _ in 0..n {
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@ -162,10 +166,6 @@ mod test {
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}
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fn measure(&mut self, n: usize, limits: [f32; 4]) {
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assert!(self.period >= 1 << self.dt2);
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assert!(self.dt2 <= self.shift_frequency);
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assert!(self.period < 1 << self.shift_frequency);
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assert!(self.period < 1 << self.shift_frequency + 1);
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let t_settle = (1 << self.shift_frequency - self.dt2 + 4)
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+ (1 << self.shift_phase - self.dt2 + 4);
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self.run(t_settle);
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@ -190,7 +190,7 @@ mod test {
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print!("{:.2e} ", rel);
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assert!(
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rel <= 1.,
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"idx {}, have |{}| > want {}",
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"idx {}, have |{:.2e}| > limit {:.2e}",
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i,
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m[i],
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limits[i]
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@ -17,7 +17,7 @@ use stabilizer::{hardware, server};
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use dsp::iir;
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use hardware::{Adc0Input, Adc1Input, Dac0Output, Dac1Output, AFE0, AFE1};
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const SCALE: f32 = ((1 << 15) - 1) as f32;
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const SCALE: f32 = i16::MAX as _;
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const TCP_RX_BUFFER_SIZE: usize = 8192;
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const TCP_TX_BUFFER_SIZE: usize = 8192;
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@ -36,7 +36,7 @@ const APP: () = {
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// Format: iir_state[ch][cascade-no][coeff]
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#[init([[iir::Vec5([0.; 5]); IIR_CASCADE_LENGTH]; 2])]
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iir_state: [[iir::Vec5; IIR_CASCADE_LENGTH]; 2],
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#[init([[iir::IIR { ba: iir::Vec5([1., 0., 0., 0., 0.]), y_offset: 0., y_min: -SCALE - 1., y_max: SCALE }; IIR_CASCADE_LENGTH]; 2])]
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#[init([[iir::IIR::new(1., -SCALE, SCALE); IIR_CASCADE_LENGTH]; 2])]
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iir_ch: [[iir::IIR; IIR_CASCADE_LENGTH]; 2],
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}
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@ -21,7 +21,7 @@ use hardware::{
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Adc0Input, Adc1Input, Dac0Output, Dac1Output, InputStamper, AFE0, AFE1,
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};
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const SCALE: f32 = ((1 << 15) - 1) as f32;
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const SCALE: f32 = i16::MAX as _;
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const TCP_RX_BUFFER_SIZE: usize = 8192;
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const TCP_TX_BUFFER_SIZE: usize = 8192;
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@ -40,7 +40,7 @@ const APP: () = {
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// Format: iir_state[ch][cascade-no][coeff]
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#[init([[iir::Vec5([0.; 5]); IIR_CASCADE_LENGTH]; 2])]
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iir_state: [[iir::Vec5; IIR_CASCADE_LENGTH]; 2],
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#[init([[iir::IIR { ba: iir::Vec5([1., 0., 0., 0., 0.]), y_offset: 0., y_min: -SCALE - 1., y_max: SCALE }; IIR_CASCADE_LENGTH]; 2])]
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#[init([[iir::IIR::new(1./(1 << 16) as f32, -SCALE, SCALE); IIR_CASCADE_LENGTH]; 2])]
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iir_ch: [[iir::IIR; IIR_CASCADE_LENGTH]; 2],
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timestamper: InputStamper,
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@ -119,21 +119,23 @@ const APP: () = {
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let (pll_phase, pll_frequency) = c.resources.pll.update(
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c.resources.timestamper.latest_timestamp().map(|t| t as i32),
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23, // relative PLL frequency bandwidth: 2**-23, TODO: expose
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22, // relative PLL phase bandwidth: 2**-22, TODO: expose
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22, // frequency settling time (log2 counter cycles), TODO: expose
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22, // phase settling time, TODO: expose
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);
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// Harmonic index of the LO: -1 to _de_modulate the fundamental (complex conjugate)
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let harmonic: i32 = -1;
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// Demodulation LO phase offset
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let phase_offset: i32 = 0;
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let sample_frequency = ((pll_frequency >> SAMPLE_BUFFER_SIZE_LOG2)
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as i32) // TODO: maybe rounding bias
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let harmonic: i32 = -1; // TODO: expose
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// Demodulation LO phase offset
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let phase_offset: i32 = 0; // TODO: expose
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let sample_frequency = ((pll_frequency
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// .wrapping_add(1 << SAMPLE_BUFFER_SIZE_LOG2 - 1) // half-up rounding bias
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>> SAMPLE_BUFFER_SIZE_LOG2) as i32)
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.wrapping_mul(harmonic);
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let sample_phase =
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phase_offset.wrapping_add(pll_phase.wrapping_mul(harmonic));
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if let Some(output) = adc_samples[0]
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let output = adc_samples[0]
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.iter()
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.zip(Accu::new(sample_phase, sample_frequency))
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// Convert to signed, MSB align the ADC sample.
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lockin.update((sample as i16 as i32) << 16, phase)
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})
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.last()
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{
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.unwrap();
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// convert i/q to power/phase,
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let power_phase = true; // TODO: expose
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let mut output = if power_phase {
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// Convert from IQ to power and phase.
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let mut power = output.abs_sqr() as _;
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let mut phase = output.arg() as _;
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[output.abs_sqr() as _, output.arg() as _]
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} else {
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[output.0 as _, output.1 as _]
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};
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// Filter power and phase through IIR filters.
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// Note: Normalization to be done in filters. Phase will wrap happily.
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for j in 0..iir_state[0].len() {
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power = iir_ch[0][j].update(&mut iir_state[0][j], power);
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phase = iir_ch[1][j].update(&mut iir_state[1][j], phase);
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// Filter power and phase through IIR filters.
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// Note: Normalization to be done in filters. Phase will wrap happily.
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for j in 0..iir_state[0].len() {
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for k in 0..output.len() {
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output[k] =
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iir_ch[k][j].update(&mut iir_state[k][j], output[k]);
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}
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}
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// Note(unsafe): range clipping to i16 is ensured by IIR filters above.
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// Convert to DAC data.
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for i in 0..dac_samples[0].len() {
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unsafe {
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dac_samples[0][i] =
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(power.to_int_unchecked::<i32>() >> 16) as u16 ^ 0x8000;
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dac_samples[1][i] =
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(phase.to_int_unchecked::<i32>() >> 16) as u16 ^ 0x8000;
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}
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// Note(unsafe): range clipping to i16 is ensured by IIR filters above.
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// Convert to DAC data.
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for i in 0..dac_samples[0].len() {
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unsafe {
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dac_samples[0][i] =
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output[0].to_int_unchecked::<i16>() as u16 ^ 0x8000;
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dac_samples[1][i] =
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output[1].to_int_unchecked::<i16>() as u16 ^ 0x8000;
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}
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}
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}
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@ -3,13 +3,16 @@
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#![no_main]
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#![cfg_attr(feature = "nightly", feature(core_intrinsics))]
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// A constant sinusoid to send on the DAC output.
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const DAC_SEQUENCE: [f32; 8] =
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[0.0, 0.707, 1.0, 0.707, 0.0, -0.707, -1.0, -0.707];
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use dsp::{iir_int, lockin::Lockin, Accu};
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use hardware::{Adc1Input, Dac0Output, Dac1Output, AFE0, AFE1};
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use stabilizer::hardware;
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use stabilizer::{hardware, SAMPLE_BUFFER_SIZE, SAMPLE_BUFFER_SIZE_LOG2};
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// A constant sinusoid to send on the DAC output.
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// Full-scale gives a +/- 10V amplitude waveform. Scale it down to give +/- 1V.
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const ONE: i16 = (0.1 * u16::MAX as f32) as _;
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const SQRT2: i16 = (ONE as f32 * 0.707) as _;
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const DAC_SEQUENCE: [i16; SAMPLE_BUFFER_SIZE] =
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[0, SQRT2, ONE, SQRT2, 0, -SQRT2, -ONE, -SQRT2]; // TODO: rotate by -2 samples to start with ONE
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#[rtic::app(device = stm32h7xx_hal::stm32, peripherals = true, monotonic = rtic::cyccnt::CYCCNT)]
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const APP: () = {
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@ -74,45 +77,48 @@ const APP: () = {
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];
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// DAC0 always generates a fixed sinusoidal output.
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for (i, value) in DAC_SEQUENCE.iter().enumerate() {
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// Full-scale gives a +/- 10V amplitude waveform. Scale it down to give +/- 1V.
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let y = value * (0.1 * i16::MAX as f32);
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// Note(unsafe): The DAC_SEQUENCE values are guaranteed to be normalized.
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let y = unsafe { y.to_int_unchecked::<i16>() };
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// Convert to DAC code
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dac_samples[0][i] = y as u16 ^ 0x8000;
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}
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dac_samples[0]
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.iter_mut()
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.zip(DAC_SEQUENCE.iter())
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.for_each(|(d, s)| *d = *s as u16 ^ 0x8000);
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// Reference phase and frequency are known.
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let pll_phase = 0;
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// 1/8 of the sample rate: log2(DAC_SEQUENCE.len()) == 3
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let pll_frequency = 1i32 << (32 - 3);
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let pll_frequency = 1i32 << (32 - SAMPLE_BUFFER_SIZE_LOG2);
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// Harmonic index of the LO: -1 to _de_modulate the fundamental
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let harmonic: i32 = -1;
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// Demodulation LO phase offset
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let phase_offset: i32 = (0.7495 * i32::MAX as f32) as i32;
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let phase_offset: i32 = (0.7495 * i32::MAX as f32) as i32; // TODO: adapt to sequence rotation above
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let sample_frequency = (pll_frequency as i32).wrapping_mul(harmonic);
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let sample_phase = phase_offset
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.wrapping_add((pll_phase as i32).wrapping_mul(harmonic));
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if let Some(output) = adc_samples
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let output = adc_samples
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.iter()
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// Zip in the LO phase.
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.zip(Accu::new(sample_phase, sample_frequency))
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// Convert to signed, MSB align the ADC sample.
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// Convert to signed, MSB align the ADC sample, update the Lockin (demodulate, filter)
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.map(|(&sample, phase)| {
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lockin.update((sample as i16 as i32) << 16, phase)
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})
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// Decimate
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.last()
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{
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// Convert from IQ to power and phase.
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let _power = output.abs_sqr();
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let phase = output.arg() >> 16;
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.unwrap();
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for value in dac_samples[1].iter_mut() {
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*value = phase as u16 ^ 0x8000;
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}
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// convert i/q to power/phase,
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let power_phase = true; // TODO: expose
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let output = if power_phase {
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// Convert from IQ to power and phase.
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[output.abs_sqr(), output.arg()]
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} else {
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[output.0, output.1]
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};
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for value in dac_samples[1].iter_mut() {
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*value = (output[1] >> 16) as u16 ^ 0x8000;
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}
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}
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Loading…
Reference in New Issue