steinhart_hart: Beta Parameter uom dimensions

The Beta Parameter is not dimensionless, and has unit kelvin.
Incorporate that into the type system.

src/channel.rs

@@ -24,7 +24,7 @@ pub struct Channel<C: ChannelPins> {
     pub vref_meas: ElectricPotential,
     pub shdn: C::Shdn,
     pub vref_pin: C::VRefPin,
-    pub itec_pin: C::ItecPin,
+    pub itec_pin: C::ITecPin,
     /// feedback from `dac` output
     pub dac_feedback_pin: C::DacFeedbackPin,
     pub tec_u_meas_pin: C::TecUMeasPin,

src/command_handler.rs

@@ -34,11 +34,13 @@ use uom::{
             ElectricPotential,
             ElectricalResistance,
             ThermodynamicTemperature,
+            TemperatureInterval,
         },
         electric_current::ampere,
         electric_potential::volt,
         electrical_resistance::ohm,
         thermodynamic_temperature::degree_celsius,
+        temperature_interval::kelvin,
     },
 };
 
@@ -243,7 +245,7 @@ impl Handler {
         use super::command_parser::ShParameter::*;
         match parameter {
             T0 => sh.t0 = ThermodynamicTemperature::new::<degree_celsius>(value),
-            B => sh.b = value,
+            B => sh.b = TemperatureInterval::new::<kelvin>(value),
             R0 => sh.r0 = ElectricalResistance::new::<ohm>(value),
         }
         send_line(socket, b"{}");

src/pins.rs

@@ -61,7 +61,7 @@ pub trait ChannelPins {
     type DacSync: OutputPin;
     type Shdn: OutputPin;
     type VRefPin;
-    type ItecPin;
+    type ITecPin;
     type DacFeedbackPin;
     type TecUMeasPin;
 }
@@ -76,7 +76,7 @@ impl ChannelPins for Channel0 {
     type DacSync = PE4<Output<PushPull>>;
     type Shdn = PE10<Output<PushPull>>;
     type VRefPin = Channel0VRef;
-    type ItecPin = PA6<Analog>;
+    type ITecPin = PA6<Analog>;
     type DacFeedbackPin = PA4<Analog>;
     type TecUMeasPin = PC2<Analog>;
 }
@@ -91,7 +91,7 @@ impl ChannelPins for Channel1 {
     type DacSync = PF6<Output<PushPull>>;
     type Shdn = PE15<Output<PushPull>>;
     type VRefPin = Channel1VRef;
-    type ItecPin = PB0<Analog>;
+    type ITecPin = PB0<Analog>;
     type DacFeedbackPin = PA5<Analog>;
     type TecUMeasPin = PC3<Analog>;
 }
@@ -108,7 +108,7 @@ pub struct ChannelPinSet<C: ChannelPins> {
     pub dac_sync: C::DacSync,
     pub shdn: C::Shdn,
     pub vref_pin: C::VRefPin,
-    pub itec_pin: C::ItecPin,
+    pub itec_pin: C::ITecPin,
     pub dac_feedback_pin: C::DacFeedbackPin,
     pub tec_u_meas_pin: C::TecUMeasPin,
 }

src/steinhart_hart.rs

@@ -3,10 +3,12 @@ use uom::si::{
     f64::{
         ElectricalResistance,
         ThermodynamicTemperature,
+        TemperatureInterval,
     },
     electrical_resistance::ohm,
     ratio::ratio,
     thermodynamic_temperature::{degree_celsius, kelvin},
+    temperature_interval::kelvin as kelvin_interval,
 };
 use serde::{Deserialize, Serialize};
 
@@ -15,17 +17,17 @@ use serde::{Deserialize, Serialize};
 pub struct Parameters {
     /// Base temperature
     pub t0: ThermodynamicTemperature,
-    /// Base resistance
+    /// Resistance at base temperature
     pub r0: ElectricalResistance,
     /// Beta
-    pub b: f64,
+    pub b: TemperatureInterval,
 }
 
 impl Parameters {
-    /// Perform the voltage to temperature conversion.
+    /// Perform the resistance to temperature conversion.
     pub fn get_temperature(&self, r: ElectricalResistance) -> ThermodynamicTemperature {
-        let inv_temp = 1.0 / self.t0.get::<kelvin>() + (r / self.r0).get::<ratio>().ln() / self.b;
-        ThermodynamicTemperature::new::<kelvin>(1.0 / inv_temp)
+        let temp = (self.t0.recip() + (r / self.r0).get::<ratio>().ln() / self.b).recip();
+        ThermodynamicTemperature::new::<kelvin>(temp.get::<kelvin_interval>())
     }
 }
 
@@ -34,7 +36,7 @@ impl Default for Parameters {
         Parameters {
             t0: ThermodynamicTemperature::new::<degree_celsius>(25.0),
             r0: ElectricalResistance::new::<ohm>(10_000.0),
-            b: 3800.0,
+            b: TemperatureInterval::new::<kelvin_interval>(3800.0),
         }
     }
 }