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lockin bins: remove stale todos, align and document [nfc]

This commit is contained in:
Robert Jördens 2021-02-23 16:57:09 +01:00
parent 6c6c2e64a7
commit e86f449dc0
2 changed files with 26 additions and 44 deletions
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21
src/bin/lockin-external.rs
View File

@ -2,12 +2,12 @@
#![no_std]
#![no_main]
use generic_array::typenum::U4;
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: () = {
@ -86,22 +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);
@ -129,7 +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()],
@ -147,7 +145,6 @@ const APP: () = {
#[idle(resources=[afes])]
fn idle(_: idle::Context) -> ! {
loop {
// TODO: Implement network interface.
cortex_m::asm::wfi();
}
}
@ -164,7 +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)]

49
src/bin/lockin-internal.rs
View File

@ -2,8 +2,8 @@
#![no_std]
#![no_main]
use generic_array::typenum::U2;
use dsp::{Accu, Complex, ComplexExt, Lockin};
use generic_array::typenum::U2;
use hardware::{Adc1Input, Dac0Output, Dac1Output, AFE0, AFE1};
use stabilizer::{hardware, hardware::design_parameters};
@ -45,24 +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;
@ -72,29 +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()
@ -110,15 +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 in 0..dac_samples[0].len() {
// DAC0 always generates a fixed sinusoidal output.
dac_samples[0][i] = DAC_SEQUENCE[i] 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();
}
}