Updating config to reject out-of-bounds amplitudes

src/bin/dual-iir.rs

@@ -29,7 +29,10 @@
 #![no_std]
 #![no_main]
 
-use core::sync::atomic::{fence, Ordering};
+use core::{
+    convert::TryInto,
+    sync::atomic::{fence, Ordering},
+};
 
 use mutex_trait::prelude::*;
 
@@ -220,8 +223,12 @@ const APP: () = {
             telemetry: TelemetryBuffer::default(),
             settings,
             signal_generator: [
-                SignalGenerator::new(settings.signal_generator[0]),
-                SignalGenerator::new(settings.signal_generator[1]),
+                SignalGenerator::new(
+                    settings.signal_generator[0].try_into().unwrap(),
+                ),
+                SignalGenerator::new(
+                    settings.signal_generator[1].try_into().unwrap(),
+                ),
             ],
         }
     }
@@ -339,8 +346,11 @@ const APP: () = {
 
         // Update the signal generators
         c.resources.signal_generator.lock(|generator| {
-            generator[0].update_waveform(settings.signal_generator[0]);
-            generator[1].update_waveform(settings.signal_generator[1]);
+            for i in 0..2 {
+                if let Ok(config) = settings.signal_generator[i].try_into() {
+                    generator[i].update_waveform(config);
+                }
+            }
         });
 
         let target = settings.stream_target.into();

src/bin/lockin.rs

@@ -28,7 +28,10 @@
 #![no_std]
 #![no_main]
 
-use core::sync::atomic::{fence, Ordering};
+use core::{
+    convert::TryFrom,
+    sync::atomic::{fence, Ordering},
+};
 
 use mutex_trait::prelude::*;
 
@@ -269,7 +272,7 @@ const APP: () = {
                     frequency_tuning_word,
                 ],
                 // 1V Amplitude
-                amplitude: DacCode::from(1.0).into(),
+                amplitude: DacCode::try_from(1.0).unwrap().into(),
 
                 signal: signal_generator::Signal::Cosine,
             }

src/hardware/dac.rs

@@ -57,6 +57,8 @@ use mutex_trait::Mutex;
 use super::design_parameters::{SampleBuffer, SAMPLE_BUFFER_SIZE};
 use super::timers;
 
+use core::convert::TryFrom;
+
 use hal::dma::{
     dma::{DMAReq, DmaConfig},
     traits::TargetAddress,
@@ -75,21 +77,23 @@ static mut DAC_BUF: [[SampleBuffer; 2]; 2] = [[[0; SAMPLE_BUFFER_SIZE]; 2]; 2];
 #[derive(Copy, Clone)]
 pub struct DacCode(pub u16);
 
-impl From<f32> for DacCode {
-    fn from(voltage: f32) -> DacCode {
+impl TryFrom<f32> for DacCode {
+    type Error = ();
+
+    fn try_from(voltage: f32) -> Result<DacCode, ()> {
         // The DAC output range in bipolar mode (including the external output op-amp) is +/- 4.096
         // V with 16-bit resolution. The anti-aliasing filter has an additional gain of 2.5.
         let dac_range = 4.096 * 2.5;
 
-        let voltage = if voltage > dac_range {
-            dac_range
+        if voltage > dac_range {
+            Err(())
         } else if voltage < -1. * dac_range {
-            -1. * dac_range
+            Err(())
         } else {
-            voltage
-        };
-
-        DacCode::from((voltage / dac_range * i16::MAX as f32) as i16)
+            Ok(DacCode::from(
+                (voltage / dac_range * i16::MAX as f32) as i16,
+            ))
+        }
     }
 }
 

src/hardware/signal_generator.rs

@@ -1,4 +1,5 @@
 use crate::hardware::{dac::DacCode, design_parameters::ADC_SAMPLE_TICKS};
+use core::convert::{TryFrom, TryInto};
 use miniconf::Miniconf;
 use serde::Deserialize;
 
@@ -45,8 +46,17 @@ impl Default for BasicConfig {
     }
 }
 
-impl From<BasicConfig> for Config {
-    fn from(config: BasicConfig) -> Config {
+/// Represents the errors that can occur when attempting to configure the signal generator.
+#[derive(Copy, Clone, Debug)]
+pub enum Error {
+    /// The provided amplitude is out-of-range.
+    InvalidAmplitude,
+}
+
+impl TryFrom<BasicConfig> for Config {
+    type Error = Error;
+
+    fn try_from(config: BasicConfig) -> Result<Config, Error> {
         // Calculate the frequency tuning words
         let frequency_tuning_word: [u32; 2] = {
             let conversion_factor =
@@ -72,20 +82,13 @@ impl From<BasicConfig> for Config {
             }
         };
 
-        // Clamp amplitude and symmetry.
-        let amplitude = if config.amplitude > 10.24 {
-            10.24
-        } else if config.amplitude < 0.0 {
-            0.0
-        } else {
-            config.amplitude
-        };
-
-        Config {
-            amplitude: DacCode::from(amplitude).into(),
+        Ok(Config {
+            amplitude: DacCode::try_from(config.amplitude)
+                .or(Err(Error::InvalidAmplitude))?
+                .into(),
             signal: config.signal,
             frequency_tuning_word,
-        }
+        })
     }
 }
 
@@ -110,7 +113,7 @@ pub struct SignalGenerator {
 impl Default for SignalGenerator {
     fn default() -> Self {
         Self {
-            config: BasicConfig::default().into(),
+            config: BasicConfig::default().try_into().unwrap(),
             phase_accumulator: 0,
         }
     }
@@ -124,16 +127,16 @@ impl SignalGenerator {
     ///
     /// # Returns
     /// The generator
-    pub fn new(config: impl Into<Config>) -> Self {
+    pub fn new(config: Config) -> Self {
         Self {
-            config: config.into(),
+            config,
             phase_accumulator: 0,
         }
     }
 
     /// Update waveform generation settings.
-    pub fn update_waveform(&mut self, new_config: impl Into<Config>) {
-        self.config = new_config.into();
+    pub fn update_waveform(&mut self, new_config: Config) {
+        self.config = new_config;
     }
 }