From 45eb55d36deea829c7dfa93b0120c7119af141c7 Mon Sep 17 00:00:00 2001
From: atse <atse@m-labs.hk>
Date: Mon, 28 Aug 2023 14:52:09 +0800
Subject: [PATCH] steinhart_hart: Beta Parameter uom dimensions

The Beta Parameter is not dimensionless, and has unit kelvin.
Incorporate that into the type system.
---
 src/command_handler.rs |  8 ++++++--
 src/steinhart_hart.rs  | 15 ++++++++-------
 2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/src/command_handler.rs b/src/command_handler.rs
index 6d4a71a..ca5542f 100644
--- a/src/command_handler.rs
+++ b/src/command_handler.rs
@@ -19,7 +19,11 @@ use uom::si::{
     electric_current::ampere,
     electric_potential::volt,
     electrical_resistance::ohm,
-    f64::{ElectricCurrent, ElectricPotential, ElectricalResistance, ThermodynamicTemperature},
+    f64::{
+        ElectricCurrent, ElectricPotential, ElectricalResistance, TemperatureInterval,
+        ThermodynamicTemperature,
+    },
+    temperature_interval::kelvin,
     thermodynamic_temperature::degree_celsius,
 };
 
@@ -248,7 +252,7 @@ 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"{}");
diff --git a/src/steinhart_hart.rs b/src/steinhart_hart.rs
index 667c587..c4f1d0a 100644
--- a/src/steinhart_hart.rs
+++ b/src/steinhart_hart.rs
@@ -2,8 +2,9 @@ use num_traits::float::Float;
 use serde::{Deserialize, Serialize};
 use uom::si::{
     electrical_resistance::ohm,
-    f64::{ElectricalResistance, ThermodynamicTemperature},
+    f64::{ElectricalResistance, TemperatureInterval, ThermodynamicTemperature},
     ratio::ratio,
+    temperature_interval::kelvin as kelvin_interval,
     thermodynamic_temperature::{degree_celsius, kelvin},
 };
 
@@ -12,17 +13,17 @@ use uom::si::{
 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>())
     }
 }
 
@@ -31,7 +32,7 @@ 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),
         }
     }
 }