From aaeb82d1998c85d3b13382ca8511399f6aca276a Mon Sep 17 00:00:00 2001
From: Christian Lind Vie Madsen <cm@oz1cm.dk>
Date: Tue, 14 Oct 2025 14:25:20 +0200
Subject: [PATCH] Added fan support, but calculation still needs to be
 verified!

---
 cm_heatsink_emulator.c | 32 ++++++++++++++++++++++++++------
 cm_heatsink_emulator.h |  8 +++++++-
 2 files changed, 33 insertions(+), 7 deletions(-)

diff --git a/cm_heatsink_emulator.c b/cm_heatsink_emulator.c
index c66f183..aca4f8c 100644
--- a/cm_heatsink_emulator.c
+++ b/cm_heatsink_emulator.c
@@ -18,10 +18,30 @@ static int isStructOk(cm_heatsinkEmul_t *inst){
 
 }
 
-static float deltaTempElement(cm_heatsink_thermalElement_t *element, float temperature, float power){
+static float deltaTempElement(cm_heatsink_thermalElement_t *element, float temperature, float power, float fan_speed){
 
-	// Kelvin = Watt * K/W
-	return (power * element->R_th);
+	if((fan_speed > 0.0) && (fan_speed <= 1.0)){
+
+		float dtemp = element->R_th_MaxFan - element->R_th_MinFan;
+		return power * (element->R_th_MinFan + (dtemp * fan_speed));
+
+	}else{
+		// Kelvin = Watt * K/W
+		return (power * element->R_th);
+	}
+
+}
+
+static float updateCthFromFan(cm_heatsink_thermalElement_t *element, float fan_speed){
+
+	if((fan_speed > 0.0) && (fan_speed <= 1.0)){
+
+		float dc = element->C_th_MaxFan - element->C_th_MinFan;
+		return (element->C_th_MinFan + (dc * fan_speed));
+
+	}else{
+		return element->C_th;
+	}
 
 }
 
@@ -34,11 +54,12 @@ int cm_heatsinkEmul_iterate(cm_heatsinkEmul_t *inst, float dtime){
 	for(int i = (inst->thermalElements_Counts-1); i >= 0; i--){
 
 		// Calculate temperature until we reach requested element!
-		dtemp += deltaTempElement(&inst->thermalElements[i], dtemp, inst->power);
+		dtemp += deltaTempElement(&inst->thermalElements[i], dtemp, inst->power, inst->fan_speed);
 
+		float C_th = updateCthFromFan(&inst->thermalElements[i], inst->fan_speed);
 
 		// Do so the temperature has the responsetime as the heatsink.
-		inst->thermalElements[i].temperature = inst->thermalElements[i].temperature + (1.0 / inst->C_th) * (dtemp - inst->thermalElements[i].temperature) * dtime;
+		inst->thermalElements[i].temperature = inst->thermalElements[i].temperature + (1.0 / C_th) * (dtemp - inst->thermalElements[i].temperature) * dtime;
 	}
 	return 0;
 
@@ -70,7 +91,6 @@ int cm_heatsinkEmul_init(cm_heatsinkEmul_t *inst, cm_heatsink_thermalElement_t *
 
 	inst->power = power;
 	inst->ambientTemp = ambientTemp;
-	inst->C_th = C_th;
 
 	// Dynamic values
 	inst->fan_speed = 0;
diff --git a/cm_heatsink_emulator.h b/cm_heatsink_emulator.h
index 7ae0b1b..538303d 100644
--- a/cm_heatsink_emulator.h
+++ b/cm_heatsink_emulator.h
@@ -18,6 +18,13 @@ typedef struct {
 	};
 	float R_th_MaxFan; // In case you need to emulate a fan
 
+	union{
+		float C_th;
+		float C_th_MinFan;
+	};
+	float C_th_MaxFan;
+
+
 	// Dynamic
 	float temperature;
 
@@ -30,7 +37,6 @@ typedef struct {
 
 	float power;
 	float ambientTemp;
-	float C_th; // Thermal capacity
 
 	// Dynamic
 	float prev_time;