Merge pull request #281 from quartiq/feature/rj/lockin-order-generic

feature/rj/lockin order generic

Cargo.lock

@@ -724,6 +724,7 @@ dependencies = [
  "dsp",
  "embedded-hal",
  "enum-iterator",
+ "generic-array 0.14.4",
  "heapless",
  "log",
  "mcp23017",

Cargo.toml

@@ -46,6 +46,7 @@ dsp = { path = "dsp" }
 ad9959 = { path = "ad9959" }
 smoltcp-nal = "0.1.0"
 miniconf = "0.1"
+generic-array = "0.14"
 
 [patch.crates-io.miniconf]
 git = "https://github.com/quartiq/miniconf.git"

dsp/src/lockin.rs

@@ -1,12 +1,12 @@
 use super::{Complex, ComplexExt, Lowpass, MulScaled};
-use generic_array::typenum::U2;
+use generic_array::ArrayLength;
 
 #[derive(Clone, Default)]
-pub struct Lockin {
-    state: [Lowpass<U2>; 2],
+pub struct Lockin<N: ArrayLength<i32>> {
+    state: [Lowpass<N>; 2],
 }
 
-impl Lockin {
+impl<N: ArrayLength<i32>> Lockin<N> {
     /// Update the lockin with a sample taken at a given phase.
     pub fn update(&mut self, sample: i32, phase: i32, k: u8) -> Complex<i32> {
         // Get the LO signal for demodulation and mix the sample;

src/bin/lockin-external.rs

@@ -2,14 +2,12 @@
 #![no_std]
 #![no_main]
 
-use stm32h7xx_hal as hal;
-
-use stabilizer::{hardware, hardware::design_parameters};
-
 use dsp::{Accu, Complex, ComplexExt, Lockin, RPLL};
+use generic_array::typenum::U4;
 use hardware::{
     Adc0Input, Adc1Input, Dac0Output, Dac1Output, InputStamper, AFE0, AFE1,
 };
+use stabilizer::{hardware, hardware::design_parameters};
 
 #[rtic::app(device = stm32h7xx_hal::stm32, peripherals = true, monotonic = rtic::cyccnt::CYCCNT)]
 const APP: () = {
@@ -20,7 +18,7 @@ const APP: () = {
 
         timestamper: InputStamper,
         pll: RPLL,
-        lockin: Lockin,
+        lockin: Lockin<U4>,
     }
 
     #[init]
@@ -88,22 +86,20 @@ const APP: () = {
             .map(|t| t as i32);
         let (pll_phase, pll_frequency) = c.resources.pll.update(
             timestamp,
-            21, // frequency settling time (log2 counter cycles), TODO: expose
-            21, // phase settling time, TODO: expose
+            21, // frequency settling time (log2 counter cycles),
+            21, // phase settling time
         );
 
         // Harmonic index of the LO: -1 to _de_modulate the fundamental (complex conjugate)
-        let harmonic: i32 = -1; // TODO: expose
+        let harmonic: i32 = -1;
 
         // Demodulation LO phase offset
-        let phase_offset: i32 = 0; // TODO: expose
+        let phase_offset: i32 = 0;
 
         // Log2 lowpass time constant
-        let time_constant: u8 = 6; // TODO: expose
+        let time_constant: u8 = 6;
 
         let sample_frequency = ((pll_frequency
-            // half-up rounding bias
-            // .wrapping_add(1 << design_parameters::SAMPLE_BUFFER_SIZE_LOG2 - 1)
             >> design_parameters::SAMPLE_BUFFER_SIZE_LOG2)
             as i32)
             .wrapping_mul(harmonic);
@@ -131,7 +127,7 @@ const APP: () = {
             Quadrature,
         }
 
-        let conf = Conf::FrequencyDiscriminator; // TODO: expose
+        let conf = Conf::FrequencyDiscriminator;
         let output = match conf {
             // Convert from IQ to power and phase.
             Conf::PowerPhase => [(output.log2() << 24) as _, output.arg()],
@@ -149,14 +145,13 @@ const APP: () = {
     #[idle(resources=[afes])]
     fn idle(_: idle::Context) -> ! {
         loop {
-            // TODO: Implement network interface.
             cortex_m::asm::wfi();
         }
     }
 
     #[task(binds = ETH, priority = 1)]
     fn eth(_: eth::Context) {
-        unsafe { hal::ethernet::interrupt_handler() }
+        unsafe { stm32h7xx_hal::ethernet::interrupt_handler() }
     }
 
     #[task(binds = SPI2, priority = 3)]
@@ -166,7 +161,7 @@ const APP: () = {
 
     #[task(binds = SPI3, priority = 3)]
     fn spi3(_: spi3::Context) {
-        panic!("ADC0 input overrun");
+        panic!("ADC1 input overrun");
     }
 
     #[task(binds = SPI4, priority = 3)]

src/bin/lockin-internal.rs

@@ -3,6 +3,7 @@
 #![no_main]
 
 use dsp::{Accu, Complex, ComplexExt, Lockin};
+use generic_array::typenum::U2;
 use hardware::{Adc1Input, Dac0Output, Dac1Output, AFE0, AFE1};
 use stabilizer::{hardware, hardware::design_parameters};
 
@@ -20,7 +21,7 @@ const APP: () = {
         adc: Adc1Input,
         dacs: (Dac0Output, Dac1Output),
 
-        lockin: Lockin,
+        lockin: Lockin<U2>,
     }
 
     #[init]
@@ -44,24 +45,13 @@ const APP: () = {
         }
     }
 
-    /// Main DSP processing routine for Stabilizer.
+    /// Main DSP processing routine.
     ///
-    /// # Note
-    /// Processing time for the DSP application code is bounded by the following constraints:
+    /// See `dual-iir` for general notes on processing time and timing.
     ///
-    /// DSP application code starts after the ADC has generated a batch of samples and must be
-    /// completed by the time the next batch of ADC samples has been acquired (plus the FIFO buffer
-    /// time). If this constraint is not met, firmware will panic due to an ADC input overrun.
-    ///
-    /// The DSP application code must also fill out the next DAC output buffer in time such that the
-    /// DAC can switch to it when it has completed the current buffer. If this constraint is not met
-    /// it's possible that old DAC codes will be generated on the output and the output samples will
-    /// be delayed by 1 batch.
-    ///
-    /// Because the ADC and DAC operate at the same rate, these two constraints actually implement
-    /// the same time bounds, meeting one also means the other is also met.
-    ///
-    /// TODO: Document
+    /// This is an implementation of an internal-reference lockin on the ADC1 signal.
+    /// The reference at f_sample/8 is output on DAC0 and the phase of the demodulated
+    /// signal on DAC1.
     #[task(binds=DMA1_STR4, resources=[adc, dacs, lockin], priority=2)]
     fn process(c: process::Context) {
         let lockin = c.resources.lockin;
@@ -71,29 +61,23 @@ const APP: () = {
             c.resources.dacs.1.acquire_buffer(),
         ];
 
-        // DAC0 always generates a fixed sinusoidal output.
-        dac_samples[0]
-            .iter_mut()
-            .zip(DAC_SEQUENCE.iter())
-            .for_each(|(d, s)| *d = *s as u16 ^ 0x8000);
-
         // Reference phase and frequency are known.
-        let pll_phase = 0;
+        let pll_phase = 0i32;
         let pll_frequency =
             1i32 << (32 - design_parameters::SAMPLE_BUFFER_SIZE_LOG2);
 
-        // Harmonic index of the LO: -1 to _de_modulate the fundamental
-        let harmonic: i32 = -1; // TODO: expose
+        // Harmonic index of the LO: -1 to _de_modulate the fundamental (complex conjugate)
+        let harmonic: i32 = -1;
 
         // Demodulation LO phase offset
-        let phase_offset: i32 = (0.25 * i32::MAX as f32) as i32; // TODO: expose
+        let phase_offset: i32 = 1 << 30;
 
         // Log2 lowpass time constant.
         let time_constant: u8 = 8;
 
         let sample_frequency = (pll_frequency as i32).wrapping_mul(harmonic);
-        let sample_phase = phase_offset
-            .wrapping_add((pll_phase as i32).wrapping_mul(harmonic));
+        let sample_phase =
+            phase_offset.wrapping_add(pll_phase.wrapping_mul(harmonic));
 
         let output: Complex<i32> = adc_samples
             .iter()
@@ -109,15 +93,17 @@ const APP: () = {
             .unwrap()
             * 2; // Full scale assuming the 2f component is gone.
 
-        for value in dac_samples[1].iter_mut() {
-            *value = (output.arg() >> 16) as u16 ^ 0x8000;
+        // Convert to DAC data.
+        for (i, data) in DAC_SEQUENCE.iter().enumerate() {
+            // DAC0 always generates a fixed sinusoidal output.
+            dac_samples[0][i] = *data as u16 ^ 0x8000;
+            dac_samples[1][i] = (output.arg() >> 16) as u16 ^ 0x8000;
         }
     }
 
     #[idle(resources=[afes])]
     fn idle(_: idle::Context) -> ! {
         loop {
-            // TODO: Implement network interface.
             cortex_m::asm::wfi();
         }
     }