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Simplifying calculation for signals

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This commit is contained in:
Ryan Summers 2021-07-19 12:46:06 +02:00
parent 6d8273ec42
commit 2f6e2a5ef5
3 changed files with 86 additions and 105 deletions
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10
src/bin/dual-iir.rs
View File

@ -120,6 +120,16 @@ pub struct Settings {
/// # Value
/// See [StreamTarget#miniconf]
stream_target: StreamTarget,
/// Specifies the config for signal generators to add on to DAC0/DAC1 outputs.
///
/// # Path
/// `signal_generator/<n>`
///
/// * <n> specifies which channel to configure. <n> := [0, 1]
///
/// # Value
/// See [signal_generator::BasicConfig#miniconf]
signal_generator: [signal_generator::BasicConfig; 2],
}

30
src/bin/lockin.rs
View File

@ -40,7 +40,6 @@ use stabilizer::{
adc::{Adc0Input, Adc1Input, AdcCode},
afe::Gain,
dac::{Dac0Output, Dac1Output, DacCode},
design_parameters,
embedded_hal::digital::v2::InputPin,
hal,
input_stamper::InputStamper,
@ -259,6 +258,23 @@ const APP: () = {
// Enable the timestamper.
stabilizer.timestamper.start();
let signal_config = {
let frequency_tuning_word =
(1u64 << (32 - configuration::SAMPLE_BUFFER_SIZE_LOG2)) as u32;
signal_generator::Config {
// Same frequency as batch size.
frequency_tuning_word: [
frequency_tuning_word,
frequency_tuning_word,
],
// 1V Amplitude
amplitude: DacCode::from(1.0).into(),
signal: signal_generator::Signal::Cosine,
}
};
init::LateResources {
afes: stabilizer.afes,
adcs: stabilizer.adcs,
@ -268,17 +284,7 @@ const APP: () = {
timestamper: stabilizer.timestamper,
telemetry: TelemetryBuffer::default(),
signal_generator: signal_generator::SignalGenerator::new(
signal_generator::Config {
// Same frequency as batch size.
frequency: (1u64
<< (32 - design_parameters::SAMPLE_BUFFER_SIZE_LOG2))
as u32,
// 1V Amplitude
amplitude: DacCode::from(1.0).into(),
signal: signal_generator::SignalConfig::Cosine,
},
signal_config,
),
settings,

151
src/hardware/signal_generator.rs
View File

@ -2,6 +2,7 @@ use crate::hardware::{dac::DacCode, design_parameters::ADC_SAMPLE_TICKS};
use miniconf::Miniconf;
use serde::Deserialize;
/// Types of signals that can be generated.
#[derive(Copy, Clone, Debug, Deserialize, Miniconf)]
pub enum Signal {
Cosine,
@ -9,11 +10,27 @@ pub enum Signal {
Triangle,
}
/// Basic configuration for a generated signal.
///
/// # Miniconf
/// `{"signal": <signal>, "frequency", 1000.0, "symmetry": 0.5, "amplitude": 1.0}`
///
/// Where `<signal>` may be any of [Signal] variants, `frequency` specifies the signal frequency
/// in Hertz, `symmetry` specifies the normalized signal symmetry which ranges from 0 - 1.0, and
/// `amplitude` specifies the signal amplitude in Volts.
#[derive(Copy, Clone, Debug, Miniconf, Deserialize)]
pub struct BasicConfig {
pub frequency: f32,
pub asymmetry: f32,
/// The signal type that should be generated. See [Signal] variants.
pub signal: Signal,
/// The frequency of the generated signal in Hertz.
pub frequency: f32,
/// The normalized symmetry of the signal. At 0% symmetry, the first half phase does not exist.
/// At 25% symmetry, the first half-phase lasts for 25% of the signal period.
pub symmetry: f32,
/// The amplitude of the output signal in volts.
pub amplitude: f32,
}
@ -21,7 +38,7 @@ impl Default for BasicConfig {
fn default() -> Self {
Self {
frequency: 1.0e3,
asymmetry: 0.0,
symmetry: 0.5,
signal: Signal::Cosine,
amplitude: 0.0,
}
@ -30,11 +47,29 @@ impl Default for BasicConfig {
impl From<BasicConfig> for Config {
fn from(config: BasicConfig) -> Config {
// Calculate the frequency tuning word
let frequency: u32 = {
// Calculate the frequency tuning words
let frequency_tuning_word: [u32; 2] = {
let conversion_factor =
ADC_SAMPLE_TICKS as f32 / 100.0e6 * (1u64 << 32) as f32;
(config.frequency * conversion_factor) as u32
if config.symmetry <= 0.0 {
[
i32::MAX as u32,
(config.frequency * conversion_factor) as u32,
]
} else if config.symmetry >= 1.0 {
[
(config.frequency * conversion_factor) as u32,
i32::MAX as u32,
]
} else {
[
(config.frequency * conversion_factor / config.symmetry)
as u32,
(config.frequency * conversion_factor
/ (1.0 - config.symmetry)) as u32,
]
}
};
// Clamp amplitude and symmetry.
@ -46,53 +81,10 @@ impl From<BasicConfig> for Config {
config.amplitude
};
let symmetry = {
let asymmetry = if config.asymmetry < -1.0 {
-1.0
} else if config.asymmetry > 1.0 {
1.0
} else {
config.asymmetry
};
(asymmetry * i32::MAX as f32) as i32
};
let signal_config = match config.signal {
Signal::Cosine => SignalConfig::Cosine,
Signal::Square => SignalConfig::Square { symmetry },
Signal::Triangle => {
let tuning_word = {
let segment_one_turns =
symmetry.wrapping_sub(i32::MIN) >> 16;
let segment_one_tw = if segment_one_turns > 0 {
u16::MAX as u32 / segment_one_turns as u32
} else {
0
};
let segment_two_turns =
i32::MAX.wrapping_sub(symmetry) >> 16;
let segment_two_tw = if segment_two_turns > 0 {
u16::MAX as u32 / segment_two_turns as u32
} else {
0
};
[segment_one_tw, segment_two_tw]
};
SignalConfig::Triangle {
symmetry,
tuning_word,
}
}
};
Config {
amplitude: DacCode::from(amplitude).into(),
signal: signal_config,
frequency,
signal: config.signal,
frequency_tuning_word,
}
}
}
@ -100,29 +92,13 @@ impl From<BasicConfig> for Config {
#[derive(Copy, Clone, Debug)]
pub struct Config {
/// The type of signal being generated
pub signal: SignalConfig,
pub signal: Signal,
/// The full-scale output code of the signal
pub amplitude: i16,
/// The frequency tuning word of the signal. Phase is incremented by this amount
pub frequency: u32,
}
#[derive(Copy, Clone, Debug)]
pub enum SignalConfig {
Cosine,
Square {
/// The phase symmetry cross-over of the waveform.
symmetry: i32,
},
Triangle {
/// The phase symmetry cross-over of the waveform.
symmetry: i32,
/// The amplitude added for each phase turn increment (different words for different
/// phases).
tuning_word: [u32; 2],
},
pub frequency_tuning_word: [u32; 2],
}
#[derive(Debug)]
@ -166,37 +142,26 @@ impl core::iter::Iterator for SignalGenerator {
/// Get the next value in the generator sequence.
fn next(&mut self) -> Option<i16> {
self.phase_accumulator =
self.phase_accumulator.wrapping_add(self.config.frequency);
self.phase_accumulator = self.phase_accumulator.wrapping_add(
if (self.phase_accumulator as i32).is_negative() {
self.config.frequency_tuning_word[0]
} else {
self.config.frequency_tuning_word[1]
},
);
let phase = self.phase_accumulator as i32;
let amplitude = match self.config.signal {
SignalConfig::Cosine => (dsp::cossin(phase).0 >> 16) as i16,
SignalConfig::Square { symmetry } => {
if phase < symmetry {
let amplitude: i16 = match self.config.signal {
Signal::Cosine => (dsp::cossin(phase).0 >> 16) as i16,
Signal::Square => {
if phase.is_negative() {
i16::MAX
} else {
i16::MIN
}
}
SignalConfig::Triangle {
symmetry,
tuning_word,
} => {
if phase < symmetry {
let segment_turns =
(phase.wrapping_sub(i32::MIN) >> 16) as u16;
i16::MIN.wrapping_add(
(tuning_word[0] * segment_turns as u32) as i16,
)
} else {
let segment_turns =
(phase.wrapping_sub(symmetry) >> 16) as u16;
i16::MAX.wrapping_sub(
(tuning_word[1] * segment_turns as u32) as i16,
)
}
}
Signal::Triangle => i16::MAX - (phase.abs() >> 15) as i16,
};
// Calculate the final output result as an i16.