From 33f4031c10bdf6d68717c16212710f432e445fd4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?sondre=20Sj=C3=B8lyst?= <sonyslyst@gmail.com>
Date: Tue, 31 Dec 2024 12:27:42 +0100
Subject: [PATCH] chore: change resistor value

---
 src/VoltmeterController.h | 62 +++++++++++++++++++++------------------
 1 file changed, 33 insertions(+), 29 deletions(-)

diff --git a/src/VoltmeterController.h b/src/VoltmeterController.h
index b7be277..529bd90 100644
--- a/src/VoltmeterController.h
+++ b/src/VoltmeterController.h
@@ -16,32 +16,32 @@ extern PRINTHelper printHelper;
 const int ANALOG_IN_PIN = A0;
 const int ANALOG_RESOLUTION = 1024;     // 10-bit resolution
 const float ANALOG_VOLTAGE = 3.32;      // Reference voltage for ESP8266 ADC
-const float R1 = 10000.0;               // 10kΩ
+const float R1 = 47000.0;               // 47kΩ
 const float R2 = 4700.0;                // 4.7kΩ
 const float CORRECTION_FACTOR = 1.218;  // multimeter voltage / voltageMeasured
 
 // Corrected constants for exponential correction
 // Constants a and b are calculated based on curve fitting using known points:
-// Point 1: (Measured Voltage: 5.25, Actual Voltage: 5.09)
-// Point 2: (Measured Voltage: 10.38, Actual Voltage: 12.65)
+// Point 1: (Measured Voltage: 5.31395, Actual Voltage: 5.03)
+// Point 2: (Measured Voltage: 13.05305, Actual Voltage: 12.59)
 // Steps to calculate a and b:
 // 1. Convert the known points to natural logarithms.
 // 2. Solve the system of linear equations to find b.
 // 3. Use b to solve for a.
 //
-// Using points (5.25, 5.09) and (10.38, 12.65):
-// ln(5.09) = ln(a) + b * ln(5.25)
-// ln(12.65) = ln(a) + b * ln(10.38)
+// Using points (5.31395, 5.03) and (13.05305, 12.59):
+// ln(5.03) = ln(a) + b * ln(5.31395)
+// ln(12.59) = ln(a) + b * ln(13.05305)
 //
 // Solve for b:
-// b = (ln(12.65) - ln(5.09)) / (ln(10.38) - ln(5.25))
-// b ≈ 1.33555
+// b = (ln(12.59) - ln(5.03)) / (ln(13.05305) - ln(5.31395))
+// b ≈ 1.02092
 //
 // Solve for a:
-// a = exp(ln(5.09) - b * ln(5.25))
-// a ≈ 0.555788
-const float a = 0.555788;
-const float b = 1.33555;
+// a = exp(ln(5.03) - b * ln(5.31395))
+// a ≈ 0.91406
+const float a = 0.91406;
+const float b = 1.02092;
 
 const int READ_VOLTAGE_DELAY = 60000;
 const int READING_VOLTAGE_BUFFER = 5;
@@ -58,44 +58,48 @@ float readVoltage() {
   Serial.print("Sensor Value: ");
   Serial.println(sensorValue);
 
+  printHelper.print("sensorValue: ");
+  printHelper.print(String(sensorValue));
+  printHelper.println(" V");
+
   // Calculate the measured voltage at the divider output
   float voltageMeasured = (ANALOG_VOLTAGE / ANALOG_RESOLUTION) * sensorValue;
-  Serial.print("Measured Voltage: ");
-  Serial.print(voltageMeasured);
+  Serial.print("voltageMeasured: ");
+  Serial.print(voltageMeasured, 5);
   Serial.println(" V");
 
-  printHelper.print("Measured Voltage: ");
-  printHelper.print(String(voltageMeasured));
+  printHelper.print("voltageMeasured: ");
+  printHelper.print(String(voltageMeasured, 5));
   printHelper.println(" V");
 
   float vinTest = voltageMeasured * ((R1 + R2) / R2);
-  Serial.print("Input Voltage: ");
-  Serial.print(vinTest);
+  Serial.print("vinTest: ");
+  Serial.print(vinTest, 5);
   Serial.println(" V");
 
-  printHelper.print("Input Voltage: ");
-  printHelper.print(String(vinTest));
+  printHelper.print("vinTest: ");
+  printHelper.print(String(vinTest, 5));
   printHelper.println(" V");
 
   // calculated correction
-  float vinTestCorrected =
+  float vinMeasuredCorrected =
       voltageMeasured * ((R1 + R2) / R2 * CORRECTION_FACTOR);
-  Serial.print("Input Voltage Corrected: ");
-  Serial.print(vinTestCorrected);
+  Serial.print("vinMeasuredCorrected: ");
+  Serial.print(vinMeasuredCorrected, 5);
   Serial.println(" V");
 
-  printHelper.print("Input Voltage Corrected: ");
-  printHelper.print(String(vinTestCorrected));
+  printHelper.print("vinMeasuredCorrected: ");
+  printHelper.print(String(vinMeasuredCorrected, 5));
   printHelper.println(" V");
 
   // exponential correction
   float vinTestCorrectedExponential = a * pow(vinTest, b);
-  Serial.print("Input Voltage exponential Corrected: ");
-  Serial.print(vinTestCorrectedExponential);
+  Serial.print("vinTestCorrectedExponential: ");
+  Serial.print(vinTestCorrectedExponential, 5);
   Serial.println(" V");
 
-  printHelper.print("Input Voltage exponential Corrected: ");
-  printHelper.print(String(vinTestCorrectedExponential));
+  printHelper.print("vinTestCorrectedExponential: ");
+  printHelper.print(String(vinTestCorrectedExponential, 5));
   printHelper.println(" V");
 
   return vinTestCorrectedExponential;