From c1b183ddd5bf4c3eccf4b40b76d92b5fe9cba62c 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 for better checks.
---
 src/command_handler.rs |  4 ++--
 src/steinhart_hart.rs  | 10 +++++-----
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/command_handler.rs b/src/command_handler.rs
index efea1b8..89052ea 100644
--- a/src/command_handler.rs
+++ b/src/command_handler.rs
@@ -38,7 +38,7 @@ use uom::{
         electric_current::ampere,
         electric_potential::volt,
         electrical_resistance::ohm,
-        thermodynamic_temperature::degree_celsius,
+        thermodynamic_temperature::{degree_celsius, kelvin},
     },
 };
 
@@ -243,7 +243,7 @@ impl Handler {
         use super::command_parser::ShParameter::*;
         match parameter {
             T0 => sh.t0 = ThermodynamicTemperature::new::<degree_celsius>(value),
-            B => sh.b = value,
+            B => sh.b = ThermodynamicTemperature::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 87149df..bca1f8b 100644
--- a/src/steinhart_hart.rs
+++ b/src/steinhart_hart.rs
@@ -15,16 +15,16 @@ 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: ThermodynamicTemperature,
 }
 
 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;
+        let inv_temp = 1.0 / self.t0.get::<kelvin>() + (r / self.r0).get::<ratio>().ln() / self.b.get::<kelvin>();
         ThermodynamicTemperature::new::<kelvin>(1.0 / inv_temp)
     }
 }
@@ -34,7 +34,7 @@ impl Default for Parameters {
         Parameters {
             t0: ThermodynamicTemperature::new::<degree_celsius>(25.0),
             r0: ElectricalResistance::new::<ohm>(10_000.0),
-            b: 3800.0,
+            b: ThermodynamicTemperature::new::<kelvin>(3800.0),
         }
     }
 }